Just watch Yannic paper explanations and research the shit that interests you specifically. If it doesn't interest you enough to drill down to the fundamentals, the field probably isn't for you. Stanford posts some good lecture series online if your interests take you towards some of those specific topics, but the bottom-up approaches that make you do complete bullshit like >>13406060
without you knowing why you need to know it are not going to get you anywhere quickly. If you're going to go through all that, at least pay for a diploma to go with it.