why do some slots have jackpots that never seem to hit

Some slots on here always advertise these huge jackpots but I never see anyone talking about actually winning them. Makes me wonder about the real odds or if the progressive ones just take ages before someone actually hits. I get that the house always wins in the long run, but some of these jackpot totals just keep climbing for what feels like forever.

I'm coming from poker where at least you know your edge or odds most of the time, but these slots are kind of a black box. Does anyone know if there are legit published odds on hitting these specific jackpots, or is it totally random and just based on play volume over time? Curious if anyone's actually seen a big one drop or knows more about how often they really hit.