I heard the theory that in the beginning, bitcoin adoption grows nostr but at some point it will flip.

Assuming this will happen, I think it's fair to say nostr adoption will outpace bitcoin adoption later on.

I also think the premise makes sense since it's easier to get started on nostr: you simply download an app which can automatically generate a key pair for you. To get started on bitcoin, you need to deal with money which you can't simply download. You can download a wallet but not satoshis.

However, there are some hidden premises like nostr surviving long enough to reach bitcoin escape velocity.