Please help, should I encourage him not to post?

My boyfriend’s dream is to be a rockstar. He loves rock music and is extremely passionate about it. He is good at guitar (he’s been playing since he was like 5 years old and self taught) but to be completely honest, he’s not the best guitar player out there. There are better guitar players on the internet. Anyway, he recently came up with the idea of posting videos of himself playing guitar on YouTube. He has a decent following already on an account he used to post rock music lyric videos. Anyway, he’s using my laptop to make these videos and I’ve been listening to them and they’re not that good. I honestly feel like it’ll be embarrassing if he posts these on the internet. For 7 years how he’s been talking nonstop about how he’s going to be a famous rockstar and I’m afraid people are going to leave mean comments about his playing (it’s his entire identity/happiness). What should I do? For context we are 22 & been together for 8 years…