i've learned the basics on youtube, and now if i want to know how to do something i can't find on youtube i ask it on the ursina's discord server
If you mean "is ursina enough to make good games" then yes you will just have to learn about optimization : limiting mesh colliders entities count and stuff like that.
but if you meant "is YouTube enough to learn ursina and make good games" then I would recommend to join the discord server. There are plenty of people who knows a lot about ursina (included it's developer) and they are always happy to help if you ask correctly (don't just say "why it doesn't work ?" Post errors and maybe the code...)