Considering you could have used the money to buy bitcoins and essentially double your money instead, what purchases did you make this year that you are now regretting?
If you knew what you know now, would you have been more frugal with your money?
Definitely on gambling and treating gambling as a way to earn easy and fast money, instead of as entertainment. Gambling is a -EV game and people don't realise that. They think that there is a strategy to beat the house, but the reality is that the more bets you make the more likely the house edge is going to catch up with you in the long term and make you lose.
I won't gamble again this year. Not after the losses that were incurred last year...