The mythological idea of them just appearing out of nowhere is nice too. Makes it feel aligned with something like the pyramids having no explanation
According to it, the sea peoples could instead be vast numbers of western europeans fleeing the outcome of a massive volcanic eruption in Iceland, which would have triggered crop failures and mass starvation in western and northern europe.
A significant portion of the survivors would have fled en masse to the richer eastern Mediterranean empires, thereby causing their downfall.
Them essentially being refugees / displaced and looking for a new place, not them being spawned on the map like a cheap rts scenario.
Similarly to the end of the bronze age, it was also a period in which shifts in climate stressed social structures. A runaway dynamic of lots of desperate people on the move is not great for stability, and if everyone is already experiencing some scarcity, then that's all the more vulnerable.