I actually don't have any regret about bitcoin. I know bitcoin lately, but I don't regret, like a question why I don't know bitcoin earlier. I'm glad that I know bitcoin even it's too late. Bitcoin have helped me a lot, so I don't mind and it doesn't matter.
That is also the same things that I was saying to my friend every time he ask me if I regret something in bitcoin. But right now, what I'm regretting is converting too early, I should have hodl it a little bit longer, if I did, I should have more profits, and that is too heartbreaking for me, a loss is still a loss. Well, that was not the biggest mistake that I've made, I'm just sharing it to you guys, because if we are really going to think of it, there is no such thing that is regretful about bitcoin.
Maybe unless you did something stupid on spending your bitcoins, for example is you lost it all in gambling, then I could say that you should really regret it.