My one big automotive regret...
Passing on a
$12,500 AU Aston Martin DB5 that need paint and a new interior. (Silver on red) Mechanically it was OK. It needed a new clutch and the basics but it was a solid car. This was about 25 years ago... I had the money but my then wife started moaning about a European holiday and stuff. That and back then they were no big deal. Even with the James Bond association it was just another old British car that needed work.
A nice DB5 is about $1.5 mil in Aus. I could retire on that amount of money right now and my lifestyle wouldn't change.
https://www.carsales.com.au/cars/details/1964-aston-martin-db5-manual/OAG-AD-18794462/?Cr=0