Thread glitched
What constitutes an amateur in chess?

The most general definition of a professional is somebody who is good enough at a craft to earn sufficient money from said craft to earn a living.
And an amateur is anyone who isnt a professional.
The only option I can see for a player with Fide ELO 2150 to make money is offering training for beginners. Not sure how much money is in that, specifically if there is enough money that you dont need to do something else, too.

The most general definition of a professional is somebody who is good enough at a craft to earn sufficient money from said craft to earn a living.
And an amateur is anyone who isnt a professional.
The only option I can see for a player with Fide ELO 2150 to make money is offering training for beginners. Not sure how much money is in that, specifically if there is enough money that you dont need to do something else, too.
I assume at 2150 you can win local tournaments for money? There are a couple of weekly tournaments near my area with a ~$300 prize pool, and $60-80 for the winner. At 2150 you might not win higher level tournaments outright but that elo would be in the top 5 players rating-wise at that tournament

Well, amateur is a broad term, but in some very strict sense, some people say that only 2 700+ rated player or top 30 player is a chess professional. It is a bit much form my point of view, but certainly someone rated around 2 200 is an amateur in a sense that he doesn't make a living thanks to his tournament winnings. Perhaps he will win some prize money here and there, but he can't really be a full time professional.
He would starve, unless he has some other income.
For instance if you take people that compete in marathon, someone who has a personal best of 2:50 is amazing compared to most recreational runners (and he might win some local race), but compared to world record holders, or those who challenge that type of people, he is generally considered an amateur, as his time is more than 45 minutes worse than that of a world record holder.
The thing is that some people compare the world amateur with a beginner or a lower rated player, and these 2 are not really the same. Even most of chess masters can't sustain themselves by just playing.

Well, amateur is a broad term, but in some very strict sense, some people say that only 2 700+ rated player or top 30 player is a chess professional. It is a bit much form my point of view, but certainly someone rated around 2 200 is an amateur in a sense that he doesn't make a living thanks to his tournament winnings.
For instance if you take people that compete in marathon, someone who has a personal best of 2:50 is amazing compared to most recreational runners, but compared to world record holders, or those who challenge that type of people, he is generally considered an amateur, as his time is more than 45 minutes worse than that of a world record holder.
The thing is that some people compare the world amateur with a beginner or a lower rated player, and these 2 are not really the same. Even most of chess masters can't sustain themselves by just playing.
That's true, but I've seen that people just make 2200 the magical cutoff line between amateur and master, which seems really weird considering in the book there is a 2175 player as an amateur (1 or 2 good tournaments could carry him over master)

I thought in chess an amateur is anyone who is untitled & below 2200 OTB, and anyone below 1000 is considered a "patzer" (although that last one probably should be removed and just grouped in with amateur)

Well, amateur is a broad term, but in some very strict sense, some people say that only 2 700+ rated player or top 30 player is a chess professional. It is a bit much form my point of view, but certainly someone rated around 2 200 is an amateur in a sense that he doesn't make a living thanks to his tournament winnings.
For instance if you take people that compete in marathon, someone who has a personal best of 2:50 is amazing compared to most recreational runners, but compared to world record holders, or those who challenge that type of people, he is generally considered an amateur, as his time is more than 45 minutes worse than that of a world record holder.
The thing is that some people compare the world amateur with a beginner or a lower rated player, and these 2 are not really the same. Even most of chess masters can't sustain themselves by just playing.
That's true, but I've seen that people just make 2200 the magical cutoff line between amateur and master, which seems really weird considering in the book there is a 2175 player as an amateur (1 or 2 good tournaments could carry him over master)
Even most masters are amateurs in a sense that they don't really have chess tournaments as their main source of income.
They are great players realistically, but chess is not football (the one you call soccer), where you have thousands of players who earn hundreds of thousands to tens of millions per year.
Someone who is ranked 100. in the world of chess perhaps can make a living by only playing tournaments, but I've seen even top 100 players advertise chess lessons in their profiles, so ... even they need to supplement their income sometimes.

I remember reading that paragraph and thinking the exact same thing. 2100 and 2150 are very very far away from Im or GM. so they're considered amateur by that standard. Just how 2100 consider 1200 as amateur. And 1200 consider 300 as amateur. It's all relative.
even this is relative. 2100 fide is usually strong enough to have multiple IM scalps and even a few GM scalps they are proud of, if they played in enough big events. They are also a threat to FMs who are not slouches.

I remember reading that paragraph and thinking the exact same thing. 2100 and 2150 are very very far away from Im or GM. so they're considered amateur by that standard. Just how 2100 consider 1200 as amateur. And 1200 consider 300 as amateur. It's all relative.
even this is relative. 2100 fide is usually strong enough to have multiple IM scalps and even a few GM scalps they are proud of, if they played in enough big events. They are also a threat to FMs who are not slouches.
Multiple IM scalps is maybe a bit excessive unless you include drawing with white!
Bit off topic but do piece colors really matter that much at high levels? Two a skilled player could draw each other, is it harder with one color than with another?

I've read somewhere that GM Luke McShane who is +2600 is considered by many the world's strongest amateur since he has a day job outside of chess.

Well I would definitely call IMs professionals. If they can already make a living from their craft is another question though.
Recently I was rereading The Amateur's Mind by Silman, and in the book he refers to players with very high ratings such as 2100 and 2150 as "amateurs". This was in 1999 and he makes references to tournament play, so I assume that it's USCF rating. What I don't get is that 2150 is very close to master (I understand there's a pretty big gap for the rating difference, but still), and yet he refers to that player as an amateur. What constitutes an amateur in chess? Is it a beginner? Time spent playing chess? Anyone who is not a master? Did the definition of amateur change since then? If anyone could clarify these questions it would be welcome.