Assuming you really mean on-demand online video/audio content (which is not limited to YouTube but also includes podcasts, Spotify, Instagram and many other pla

Assuming you really mean on-demand online video/audio content (which is not limited to YouTube but also includes podcasts, Spotify, Instagram and many other platforms that may or may not yet exist), there is still huge growth potential and limitless opportunities for new content. If you chronologically relate it to the history of television, on-demand online content is at the equivalent of about 1965. There's still a huge amount of the global population that doesn't really listen to much of this kind of content passively - e.g., while driving/commuting, working, exercising, etc, as many people still don't even know you can really do this. And mobile data is still expensive in a lot of places in the world. So, I can easily see the audience scale (measured by hours consumed) increasing another 10-20x in the next 10-20 years. Even then, I doubt there's anyone, even people (like me) who spend many hours a week consuming online media, who thinks "there's no room in my life for anything other than what already exists". So, no, it's not too late, and indeed it's never too late. But you need to figure out what is the unmet need that you can fill, then work hard over a long period of time to deliver something special for your audience.