Did I play bad, or did my opponent play good?

I just drew a 650 rated player, while being 1750 rated myself in blitz. My estimated win chance should be 99.83% based on elo difference, so a draw would seem a very unlikely result. The rating difference is equivalent to me drawing a 2850 rated player (which I don't see happening) So for me, this puts the legitimacy of the elo system in question, also because the theoretical win-chance does not seem to correlate with the actual win-chance.

Anyway, I know I missed some pretty obvious tactics in the endgame, but that's also because my opponent put the pressure on the clock. Did my chess just suck that game, or did my opponent outperform?

The game in question: https://www.chess.com/game/live/148320494604

I really like the chess.com rating system (which is actually glicko 2.0 last I heard, rather than elo, but they are very similar), but comparing the win percentage to rating has some drawbacks to it. You can mathematically estimate via ratings, but it's only an estimation at best; it doesn't take into account, playstyles, opening knowledge, playing environment, or many other factors which could impact the true winning percentage for each player.

There's also likely a greater chance for a draw at the higher ratings than lower ratings, so it isn't really equivalent to take the rating gap of you and the opponent and then apply it to compare you to a 2850 rated player.

That being said, I can still take a look at the game for my opinion on it.

Yes please

Here's the two videos I referenced in my analysis:

Now check out some videos, or games, where I play better than this

Actually, looking at the game, I just think there were far too many trades. All they did was not make a catastrophic blunder, win their pawns back because they were hard to defend, and then it was just a drawn endgame, and all they needed was a simple sacrifice. I guess you could say they outperformed their rating, missed a few tactics, but got lucky later on. I think you anticipated a blunder, played a little inaccurate to try and get that, and it just didn't happen. It also seems that you played too quick at some moments.

I looked a bit more in detail, and they did make some blunders, but didn't make it the easiest to win. The endgame was a bit tricky, and just the nature of it, despite an advantage, meant that it was a critical moment that would be hard to play with lower time, and so go to a draw no matter what.

Game Rating had you with 9 Inaccuracies, 2 Mistakes, 2 Misses and 2 Blunders, and both of you at 81.2 and 81.1, for what it's worth.