We have 10x leverage on mechanically identical stock derivatives in Sweden and for indices much higher.
They're not dangerous per se if you understand that eventually they will end up at zero and you need to sell before then. The issue rather is volatility drag and the fact most return sequences are not favorable to daily rebalancing of high leverage. So although you have some instances where somebody could bag >100000% returns on Tesla in a few months in most cases they lose money, i.e. quite similar to lotteries.
From last year there are some instruments in cocoa that are up a million percent etc. Fun to think about from a backtrading perspective but nobody likely held on for so long for fear of having their paper profits evaporate to zero on a bad day.