It is entirely possible to learn by yourself online. I did it! But a warning: you will spend years in the weeds, focusing on things that don't matter. Good in-person advisors can help you avoid some years wasted time.
The fastest way to learn is to move to the Bay Area and work with people who have been doing this for decades. That is not a sufficient criteria (anyone can be a bad teacher), but the experience is extremely useful.
> But a warning: you will spend years in the weeds, focusing on things that don't matter.
That sums up anyone's college experience.
The hard part is telling apart what doesn't matter from what does. More often than not, what dictates which is which is the project you find yourself working on.
You can learn from everyone around you, regardless of their status. There is no "universal developer experience curve", everyone has more or less knowledge on a field or with a specific tool/framework.
You can learn almost everything alone - I mean learning from the web. There are great forums, groups, discord chats, ask LLMs carefully and check on the answers. It may sound reassuring that someone watches your back and won't allow mistakes or would help clean up a mess, but you should not keep relying on this anyway. Learning by doing and taking responsibility will make you much more self assured, which is actually most of what makes someone senior.
There's a big difference between learning from someone and having someone teach you something. The latter expedites your progress and clarifies learning path, whereas the former can even waste your time with political fights pulling you into dead-ends.