This is actually more because criminals on balance tend to be too dumb to hide their traces than because of any demographic truth. There are a lot of criminals.

Focusing on "crypto" is, I think, a forest for the trees argument. Look instead at anonymity for evidence of where this kind of thing goes. Put up any reasonably anonymous forum where people can interact without their identities being reveals (which often includes, but doesn't always require, some kind of crypto protocol). Within a year it will be filled with criminals. Minor criminals like drug dealers. Worse things like market manipulation and fraudsters. Weapons sales. Black market rings. Revolutionaries of all sorts and sizes. Child porn. Mail order brides and other trafficking trades.

Seriously, run a Tor exit node for a while and see where this goes.

Your neighbors in your imagined "safe haven country for cryptographers" aren't going to be who you think they are.