Chess isn't fun for me anymore

A lot of them are from playing low elo friends of mine. Whenever I get to 1600-1700 I tilt and get squashed repeatedly back down to 1500

It looks like you've been improving rapidly and have gotten to 1500 in 76 games! It took me a good 2000 games to get to 1500. I understand, chess can be frustrating, but we all make mistakes, and eventually you will improve. If it isn't fun for you anymore, that is understandable, you should try to take a break from chess, but from my viewpoint, you're doing great.

I'm constantly losing from stupid blunders. I don't improve anymore. It doesn't matter how many puzzles I do, or instructional videos I watch, or games I analyze. I've been stuck at this rating for 15 years. I can't deal with this game anymore.
Sure, chess is boring. Let's all take upa different game. How about Simon Says?
Simon says pick your nose
Simon says scratch your butt
Simon says put finger that picked nose into mouth
Get out the toilet paper

When I was a beginner, I always looked for ways to stop making blunders, my research were mainly tips on how to stop blundering. Well, here I am 2000+ rapid and I still make blunders in one move.
Super GMs in the FIDE world championship made some blunders even when they had a lot of time on their clock. All these said, as long as you are a chess players, blunders will always happen.
Look into your openings, have some endgame knowledge, do puzzles to sharpen you tactics. All these will be useful for your improvement. Also try to analyze your games learn from your mistakes. You shouldn't beat yourself too much about blunders, we all make them.
I'm constantly losing from stupid blunders. I don't improve anymore. It doesn't matter how many puzzles I do, or instructional videos I watch, or games I analyze. I've been stuck at this rating for 15 years. I can't deal with this game anymore.