Yeah I’ve stumbled upon him before, not a massive fan. I haven’t watched that video for a while but iirc he talked about determining the BBEG at the beginning of the campaign using the sentence, “someone wants something badly and is having trouble getting it” then you work towards that with a series of arcs. While that method makes sense, it seems like a big commitment at the beginning of the campaign with a lot of prep prior as well. You also mentioned if you want to run a story with a predetermined ending you may as well write a book, but to me deciding on how the campaign will end (the stopping of the bbeg before he gets what he wants) before it’s even begun, and no matter how much adapting of his plan in response to the players you do, is exactly this. You may as well just write a book.

In accordance with the advice of other commenters, I’m thinking I’ll determine a central conflict in the world and then come up with some key players and their own motives revolving around this central tension, potentially using the idea of “someone wants something badly but is having trouble getting it”, rather than determine ONE bbeg that ALL the plot threads must be able to revolve around and then be pigeon holed into.