so its very possible to be IM, but it takes more effort, preparation, luck and I would say a number of events to be a GM and have the 2600 performance.
What I mean is that, if your IM strength, or something that would score 5.0 to 6.5 points all the time in a event with a cross table like the one above, it would mean that if you play 50 to 100 tournaments in a 10 year time period, you could become GM.
I was investigating the nuances on becoming a GM. I am an FM with a FIDE rating of 2287.
after reading this article: https://www.chess.com/article/view/how-to-become-a-chess-grandmaster
I wanted to see how hard it would be to have a 2600 performance and find events where you could compete, etc etc.
Well everyone knows about the events in Budapest every first saturday at http://www.firstsaturday.hu/1812/index.htm
this is a cross table of their events for GMs:
http://chess-results.com/tnr396836.aspx?lan=1&art=1&flag=30
Basically, to make a GM norm you have to make 7.0 points out of 9.0 to make a GM norm, atleast with that crosstable to have the 2600 performance needed by FIDE to make the norm.
this is quite frankly difficult. what we appreciate is that now we understand what a 2600 performance is.
to appreciate how hard that is,: your playing 9 players: three 2500's, three 2400's, and three 2300's
which means, you have to beat the 2300's (3pts)
beat the 2400's (3pts)
and draw two 2500's, or beat one, and lose versus the rest to make a total of 7.0 pts at the event.
Pretty insane right?
it possible for a 2300 FM to beat three 2300's and three 2400's with training and preparation, but the 2500's performance adds an element of luck to the formula. In other words, performing versus the 2500's is more complicated.