Cats can get into houses just fine.
Also, having eight legs would make large spiders behave like giant hands, so opening windows and doors might be an easy task for them. Especially if multiple spiders cooperate…

nah nope thats like being afraid a lion will hide itself under your toilet lid to jump you when you go piss in the middle of the night.

if spiders were big we would find it easier (or necessary) to keep them under control.