Worth noting that MBTI has a well-documented retest problem. About 50% of people get a different type when retested within 5 weeks. The letters themselves are shaky ground.

But the INTJ overrepresentation here is actually real signal hiding behind bad instrument. When researchers use the Big Five model instead, Bitcoiners consistently score high on "need for cognition" scales, plus high openness-to-experience combined with low agreeableness. That specific combination predicts early adoption of novel financial instruments going back to derivatives traders in the 1970s.

The Brazilian replication is interesting for a different reason. Brazil has the highest per-capita crypto adoption in Latin America, but the personality distribution barely shifted from the US sample. That suggests the personality filter is stronger than the cultural one. The protocol self-selects for a cognitive profile regardless of where you are on the map.