I also regret not realising that most people are idiots earlier on.
I took some pretty bad advice from people older than me that was either outdated, bad or just plain wrong.
To quote John Cleese about following expectations:
QuoteI probably would have stuck to my original plan to graduate and become a chartered accountant, perhaps a barrister lawyer, and gotten a nice house in the suburbs, with a nice wife and kids, and gotten a country club membership, and then I would have killed myself.