[DanBC]

People use it because the products sound neat, and there's no friction, and then they keep using them because there's friction to move away.

"Free email, with 1 GB of email storage? Neat". "Nice fast web-browser, nice features? Neat!" etc etc.

People on HN do AB testing for button colours in an effort to reduce friction to the lowest possible. It's not that surprising that people think "it wont happen to me".

See also people who never make backups until they learn the lesson that first time they lose everything.