Though unlikely, Trump could (conceivably) win, ditch Ukraine exactly as promised (not in 24 hours but over time), which would of course deeply embolden Putin (and/or lead to a nuclear escalation in itself, particularly if Ukraine does something really desperate). Putin could die (or be assassinated) and easily be replaced with someone way more ideological and/or simply stupid.
Farther afield: though it would irrational in every respect -- China could make its move on Taiwan. And as always, in the Middle East, anything can happen (especially if the current government in Israel stays in power and continues to radicalize and throw oil on the fire).
Any of these could escalate on its own. But it is the prospect of the these three theatres deteriorating rapidly at once that has people up at night. Not so much on WWI or WWII lines, but a different kind of global conflagration altogether.
I'm not a doomer on the prospect, but it's by no means out of the question. These are indeed very unsafe times.
(As an aside, and in line with what the other commenter, it's just not true to say that Palestine's neighbors "don't give a shit". Their interest may not be altruistic, but to many of them the situation there is deeply significant, for a host of geopolitical, ideological, and religious reasons).