Why am I still terrible

I am a self taught guitarist, been playing for three years about one and a half years actually playing. I have made absolutely no progress, I am as good as I was after playing for five months. I am so bad and everything feels wrong. I can't make any riffs sound good no matter how many times I practice playing them. I slow them down and they still sounds shit. People say to play for fun and I do have fun when I crank the distortion up so I can't hear my mistakes. I am about to quit again but my parents have spent a lot of money on my equipment so I feel really bad.