Maybe this guy retired before his parents did.
I could retire now but choose to keep working because I like it (most days), the money is good and my work gives me travel opportunities that I wouldn't otherwise have.
Everyone is different. I knew a guy who retired before age 40. I think he's happy; I wouldn't be. Anyone who retires really early has to think of what they would do for potentially 60 years or more of full- or part-time retirement.
Interesting conversation.