Start by having your badminton coach introduce you to a group that regularly plays at your place of practice. Once you get to know them and they know you better, they will extend the invite.
I say that because KTV/drinking/eating out are the norm and any group of people with any kinds of hobbies will do those three activities on top of their hobby or as a way to wind down.
I don't want to sound too harsh, but if you find yourself in the midst of young dads, that's probably not the best group of people to hang out with. Their time will be consumed by kid/wife and any extra time they have, they will be "hobbying". Their eating out/KTV/drinking days are well behind them.