I made a million on one platform by ignoring all the others

"Be everywhere" sounds like good advice until you're spread thin across five platforms, seeing results on none of them, and quitting before anything has time to compound. Learning an algorithm is like learning a city. You can't know five deeply at the same time. The question isn't which platforms you should be on. It's where your buyers already are, and how fast you can own that channel before everyone else does.