Simple question: how many pins can you have set up and running right now in your house? If you have a building for your pins on your property, include that. Don't include future expansion plans, or space that's currently "disputed" territory (e.g. the dining room - for 80% of us, that belongs to our spouses).
If you have space ready for more pins than you own, answer for space. Let's make this a snapshot of Pinball Homeland territory right now.
I know a guy who had 50+ games set up in his <3000 s.f. home. But for me, it's 16 pins in our 1500 s.f. basement, with no plans for expansion. The rest of my games are in a storage unit.