Do whatever you want, so long as it’s not negatively affecting anyone else. Otherwise, you’re outvoted by everyone else who also only lives once and doesn’t need your asshattery screwing it up.
Reminds me of the “I’m just telling it like it is/keeping it real” excuse for being rude or cruel. Use YOLO for stuff like trying a new career, joining the Peace Corps, asking someone out, etc., not for cheating on your spouse, casual sex without protection, blowing off your best friends for the dude of the week, spending the rent money on other things, trying hard drugs, etc.
or the whole ‘inner child’ thing as an excuse to be childish and petty and an asshole about not seeing to ones responsibilities, instead of being childlike, having an air of wonder and discovery.
For me, YOLO is made in response to people that say things like I would love to travel to XYZ, but never make plans to do it, always have some sort of excuse to not go, etc. Or wish they had learned to play the piano or taken art lessons, etc.
They can still do those things, but they’re not going to get a second lifetime to do the things they regret never doing in this lifetime.