Well, I guess you just did, so there you go.
I don’t think people should ride without trainers if they want to get better in their riding and/or compete. As I mentioned above, everyone- from beginners to Olympians- benefits from at least (educated) eyes on the ground. Even if it is one lesson a month, which is what I was able to manage for a while because my trainer at the time was far away, that’s better than nothing. It’s a chance to check in with someone knowledgeable who can give you homework, correct issues, provide a new lens on training problems, notice things about your horse(s) that you’ve missed or gotten used to, etc.
If all you want to do is be at the level you are at, you feel confident, you have no higher aspirations in your own education, you don’t show or whatever level you are showing at is very comfortable for you and your horses, then yeah, skip it. Have fun with your horses, dork around, practice things you know, whatever. Plenty of people do that and that’s great. But if you want to learn and advance your and/or your horses’ training, tackle a new level or discipline, solve training problems, well, I think you need more than youtube and a few books.