I defeated an opponent with a 2050 rating. What did I not do wrong?

your oponent just blundered and lost the exchange at the end, before that he seemed to be outplaying you.

sometimes people does mistakes. kramnik missed a mate in one against deep fritz. it doesnt mean that kramniks real rating is around 900:)

why do you take pride in this game?
While I understand that my level of play is profoundly inferior to that of the average person with a 2000 rating, I'm glad I was able to survive for over 60 moves. I thought I wasn't going to make it past the opening.

In fairness, you did hang pawns at move 13 and 18, giving black a technically won game. And he continued to play it fine simply building on his two pawn advantage until his material losing blunders. I wouldn't be so giddy about giving up two pawns just so I could trade a bunch of pieces and force my opponent to take a lot of moves to beat me. In your case it worked out because he eventually blundered.

In fairness, you did hang pawns at move 13 and 18, giving black a technically won game. And he continued to play it fine simply building on his two pawn advantage until his material losing blunders. I wouldn't be so giddy about giving up two pawns just so I could trade a bunch of pieces and force my opponent to take a lot of moves to beat me. In your case it worked out because he eventually blundered.
Thanks for giving me credit for coming up with such a clever stratagem to slow down the game as much as possible, but the truth is that my hanging pawns at moves 13 and 18 were blunders any person with my rating can make. My opponent, on the other hand, also made at least two blunders, which even I was able to detect. Those blunders, while very human and forgivable, are not expected from a person with a 2000 rating and certainly not while playing against a presumably vastly inferior opponent.

You shouldn't make assumptions about someone's playing level from a single game, especially not on the Internet. People play here tired, in a bad mood, drunk etc. It is also possible that they are trying things, experimenting with new lines etc and not playing as if it were a WC match, which would be pretty logical since obviously it isn't. Let's say that you played reasonably well and somehow happened to win.

congratulations man, every game ends in a win, and sometimes the lower rated one is the winner. you won, enjoy it!!!!

You played pretty well. The higher rated player made a mistake and you won. It happens sometimes. Next time you beat someone over 2000 you won't have to start a post about it.