In cash games? I see it once in a while in micro/mid stakes after someone tilts from taking a bad beat or making a bad call. They'll start spewing chips by shoving for several hands until either a) other people call them and take enough buy-ins that they rage-quit the table, b) people call and they win enough to "calm then down." or c) no one calls and they eventually just settle down after picking up a few blinds.
I've also seen it where I've sat down at a table where someone already has 5x the buy-in and are intermittently shoving preflop, and somehow keep winning. I'm not sure what is going on in their mind, but if they are "feeling lucky" and keep being paid off it might keep reinforcing that decision until they lose a hand, and then the player eventually leaves with their winnings from that table. We all know it can't work well for them long term, but I don't know if that's how they play
all the time but I'm sure it feels sweet winning a bunch of money in a short period of time.
As far as tournaments, I see it mainly at the beginning of
freerolls and rebuy MTTs. They are a massive time commitment, and you aren't losing much, if anything if you bust. If you
do get lucky you're in a good spot for the long haul. Personally, I don't mind that because the field thins quicker and if the gods are good I might get a hand worth calling with (I've become the overall chip leader on a couple of occasions from a single, early hand).
Overall, I don't believe people who are all-in/spam-shoving every hand in general are taking the game all that seriously at the point, no matter the format.