This is a good question to ask! I think it's a lot like learning music where you can do a lot on your own--and there's a lot of online resources available. But, no matter what instrument you may learn, you can't learn as quickly without the help of an instructor. Art is the same way. It also helps to clarify things that are kind of vague online, there's also a ton of misinformation online about art, so taking classes can be beneficial.
There are way cheaper alternatives than just going to Calarts or whatever. I did a University because my education was way cheaper. Universities have way more scholarship opportunities (art schools have way less) and although I didn't have the connections that a private art school would have, I still wasn't sure if it was exactly what I wanted at the time, so it made sense for me. I also took classes at a community college where it was like...50 bucks a semester. It was really affordable and you can be taking things like gesture drawing or figure drawing without spending 6 grand a class.
Artists will also offer classes independant of art school, especially right now. There is atelier style teaching if you want to do really fine art, there's classes you can purchase online where you have mentorship with your professor who is a person in the field several times a week. (things like schoolism is ok, I've taken schoolism classes before.)
So it's not a losing battle at all. There's plenty of artist who never had a private art school instruction, you just have to discipline yourself and reach out. After I finished university I've continued taking classes and courses in different things, so it's pretty normal to supplament your learning with just...whatever's available, and a lot of that is online and from books and things like that.