I don't think gambling is wrong but just don't be addicted. I love playing it, but not betting so much money.
You are right, gambling is not wrong because it was designed to give us fun and entertainment. But if we go greedy, then that is the start of a miserable life much more if we get hooked on gambling. So, better gamble for fun and entertainment with the money that we can afford to lose.
Gambling do gives us entertainment and happiness, but this doesn't mean that this is not wrong. Gambling is wrong, because instead that we could earn money we are just losing it. We have earned that bitcoin in a good way and yet we are just going to spend it on gambling, don't you think it is not worth it.
All the hardworks, efforts, and the sleepless night that we do have just to earn this bitcoin will be useless because wr are going to use it or it will be lost in gambling.
Well think about this way, if you gambling for entertainment is not wrong, it is true that it spending your money but it's not 100% lost, you go to watch a movie or playing video game, it is also spending your money, so gambling is just spending money to release your stress, the one that make gambling is wrong when you hurt someone because of gambling, you neglected your family because of gambling and you used the money that you not supposed to used for gambling eventhough that you are winning that is still wrong