Recently I saw a great post on Whirlpool.net.au which basically described YOLO trading as essentially abandoning risk management and position sizing on the basis of you only live once (and the post essentially surmised that it mostly younger investors - not so sure on that one but possibly I guess).
From my perspective, I essentially see a YOLO trade as putting it all on black at roulette table. You've got a basically 50/50 chance that you lose or win the trade.
Statstically speaking you could have a series of wins (and you see this in posts on rWSB, Whirlpool, rASX_bets and various other trading groups and forums), but eventually the stats wil revert to mean and those traders lose the lot, particularly if a series of wins has build an attitude of it will bounce back.
Essentially I think an all bet is just a symptom of the get rich quick mentality that many have and incredibly dangerous to long term success in this game.