Why is it easier against stronger opponents?

Why is it easier against stronger opponents? I usually win when I meet someone with a higher rating, preferably 2-300 over. But I can struggle against players with far lower ratings than myself. Frustrating that I am so unstable, and the losses to players I "should" have beaten, make it difficult to climb.

Psychology
Against a weaker player you expect an easy game, you lower your guard and you are more likely to make mistakes.
Against a stronger opponent you think carefully and you give your best effort.

I think it’s just the mentality. When we play people rated lower than us, say 100 points or more, we feel like we are meant to win, like we deserve to win. So when we make bad moves, or we’re in a tough position, we often get frustrated, which leads to more mistakes. Compare that to playing someone a 100 points or more higher rated than you. You feel like you are expected by everyone to lose, you’re the underdog. And so being in a losing position doesn’t frustrate you, because you had already told yourself you were unlikely to win. That also means that you want to prove yourself, and pull off a win. So without frustration, you play your best, and you don’t mind if you win or lose. The reality of it all is, the higher rated opponent might have played weaker than the lower rated one did, because 100 elo is not much of a difference, your mentality is. As Fischer said “I don’t believe in Psychology, I believe in good moves.”

I agree. I'm happy to play a higher rated opp cause i don't mind if I lose, but if i play a lower rated player, it feels like im expected to win and that gives me pressure. Thanks for this conversation, @NordeggenChess!

Also, part of it can be the fact that lower rated players play worse moves... meaning moves you didn't calculate during your turn, so now you have to do more calculation.

If a high rated player is playing the good moves you expect sometimes that's easier (at least in terms of calculation).

But sure, getting bad positions against players who are worse than you is often psychology. Don't think about how you should win, just try to find quality moves. Eventually they'll blunder.

One thing I noticed, was that the openings were pretty solid in a lower rating, but then as i got a little higher rated opponent, they played a little more dynamically and aggressively, sometimes to their detriment because we are still amateurs and miss stuff like long term positional considerations. A lower rated opponent I may end up losing to because they may be sticking to a more solid opening, and I overextend trying to win by rating alone, which chess doesn't care about, so when I try to do something fancy in a position that doesn't warrant it, I just end up in a worse position which my opponent cleans up. 

I also think that although it is rarely a conscious decision, often times we copy our opponents playing style. If they are making clueless moves, we often do the same. Where as when you play a strong player, the game is much more interesting. All of their moves, make sense, and so you respond with good moves also. I am rated between 500 and 600. I love to play strong players, win or lose. I have enjoyed games from 500 to 1200. I don't win them all, but they are always fun. Still when the game sends me a 300 - 400 rated player, I become very worried. The games are never fun.

I think it's relative to rating. I hover between 1200-1300 and I've noticed that I'm stronger at that range than say against the occasional 1000-1200. With a 1250-ish or higher player I can trust they'll play five to seven book moves that look familiar. I know the plans, hopefully. That makes it easier in some sense. The 1000-ish will more often make a non-book move sooner. Whether the player knows this, this can be an effective strategy. If your wins are dependent on theory instead of actual positional understanding the player may just draw you into a deep, dark forest. A sharp position can favor the lower rated player by increasing the chance for mistakes. I've had more success by reversing the script. With lower rated players I try to induce positional weaknesses: over extended structures, backwards pawns, fighting for color structures and squares, etc. It's a slog. But patiently waiting for the position to bear fruit, or your opponent to finally make a tactical blunder, usually makes for an easier win. With 1300+ players I'll try to play gambit lines, or make a 'good,' but not stockfish approved move. Anything to keep it asymmetrical or open. If you were 1500+ this may not be effective. Advanced players, for me, usually see through my shenanigans. Titled players often suggest a 20:40:40 split for studying openings, tactics, and endgames. If I stick that, and studying pawn structures more than openings, my rating always goes up. Go figure. It's like they might be on to something. Hope that helps. 😀