you should not be too regretful, take advantage of the existing situation, when the cheap price always try to buy coin and sell when the price is green and when it is getting the benefits and better you control your patience.
You can handle crypto regret by not repeating the mistakes you made in past. Keep looking at the market condition and start modifying your plan to stay safe. Keep the investment long term and stay optimistic by which I mean to say do not panic. You will be able to kill the crypto regret when you earn again big with your mental capabilities and market knowledge by playing the same crypto game.
Guys forget about the past. Past is dead. Try to concentrate on the future and this will make you concentrate on your future transactions. You need to learn from the past lessons. Then you will be more responsible in your exchange transactions.