I think the worst mistake that i have ever done in gambling is being greedy I mean I have won a decent amount of money from my 0.0002 and I put it all in, in a round in satoshimines then my mouse was click by other person while i was talking to my friend hehe so i learned a lesson that I should never leave my mouse when i'm playing satoshimines
Gambling is a fun game so you learned that lesson in a hard way and find out that we can't win money in gambling. I suggest don't ever go to gambling to make a money because you will most of the time end up losing money and will not enjoy any games and always in a stress to get back your lost money.
That's given that most of us are all gambling for the sake of good profit that we may get. It is good if we are just moderating the way we gamble but if that is too much then that is not making you to be productive in gambling for you are all thinking about profit that can lead into greediness which is the root of all cause of our fall down and for having mistakes with our decision making as we gamble.
PS, let it go, you can't complain about it and just learn from it. 
Seriously, there are thing called carelessness, which is often called a newbie mistake, instead of losing just a small amount, you lost a bigger amount due to the fact that you are not paying attention. And that is a mistake. Another thing is pushing things that you are well aware that will most likely lose. anything that does not go along with your planned strategy is a mistake. Or a strategy that result in a catastrophic lost is also a mistake. Or breaking your rules and strategy that result in a bigger lost is also a mistake. Being too greedy is also a mistake. Any action that make you lose more than usual is a mistake.
