While I appreciated your source
1.) I doubt 99% of Europeans work during 3am - 9am
2.) At least there can be other reasons:
2a.) EU times and African times are basically the same and Africa has a huge population.
2b.) India is closer timewise to EU/African time zones
2c.) What are about posts afterworks?
" RL conversation topics in the Bay Area tech scene are entirely different from those on HN shows a massive divergence in userbase. "
Any proof?