My son and DIL have two cats that are infatuated with boxes to the point they don’t play with cat toys.
The wife and I have seven of them. Five were rescued from shelters and two showed up on the back porch as kittens sleeping in one of my wife’s big flower pots.
They love hiding in boxes or in this little space between our furnace and water heater.
I think they just like the ability to find some little place they can hide.