hmm. it might be a bit more subtle than that - if you were to own all 21 million bitcoin (i.e, nothing can be mined or otherwise created), it’d pose an existential crisis for the currency. miners would have no reason to mine, transactions on the small scale couldn’t happen, etc.

at the very least i expect other coins would pop up with a different genesis block. or maybe some form of hard fork (again, i might add).

owning them all might be problematic. 99% might not be.

that said, i don’t think it can be done for >100 years yet..