From speaking with people who work for OpenAI, Meta, and xAI:
1) They don't believe the harmful things they're being warned of will affect them. They won't believe those are real problems until those problems affect them personally.
2) They believe that if they don't do the work, someone else will, so they might as well be the one getting paid for it.
3) They have a graduate degree in ML or AI and they don't see a path to a similarly paying job in another field given their work experience and credentials.