Sometimes, one of the domains you should have bought but didn’t ends up selling for a pretty penny and you regret not buying it.
Sometimes, you miss opportunities to multiply your money by a factor of 500 (for example, by buying Bitcoins at $0.05 and selling at $250) or 50 (for example, by buying AAPL at $10 and selling at $500).
… and so on.
It happens.
ALL the time.
Making financial decisions based on an “I didn’t take advantage of a great opportunity back then but I’ll compensate now” impulse is a good way to end up bankrupt.
At the risk of being repetitive: try to avoid emotional decisions and do everything you can to make rational ones.
Nobody’s perfect and there will always be missed opportunities.
Don’t let them cloud your judgment.
Analyze each opportunity on a case by case basis.
If the opportunity makes financial sense, go for it. Just don’t make decisions for the wrong reason.