Why do I self-sabotage and what can I do to stop it?

Hi!

I recently became a streamer and I've been doing this challenge in a game over the course of weeks and as soon as it looked like there was no way that I could lose, I started throwing every game like I had never even played before. I realize I do this all the time though.

- When my marketing was doing well and I was about to hit my goals, I just stopped posting.

- When I used to compete, if it was a sure win, I would literally hit every shot into the ground.

- Even when I was playing fortnite with a friend once, he was like oh my gosh, you're so good. Comp will be so easy, and again it was like I forgot to play. It was so bad I fell off cliffs multiple times.

- When I'm about to hit a weight or exercise goal, I just stop exercising and eat like crazy.

I recently realized it could be self-sabotage but whyyyyy and what do I do??