Asklemmy

Model Railroading.

It's not the worst, but it requires all the key ingredients - you need to own a home large enough to have a 'spare' room, which means you've got disposable income. And displaying the trains is almost as much fun as running them, so you end building shelves and shelves, which then sprawl out to the rest of the house. Only to realize you're missing the 'key' one from that set, got to go find that, obviously.

And then of course you can't throw away the boxes, because that would lower the resale value, so you need to rent a second storage unit. Not that you would ever sell them of course. But your kids will be sitting on a goldmine!

And that's just the collection portion. It's a crafty hobby, from making scenery & waterfalls & little trees all the way to the special paints to make the engines look aged. That will need a room as well.

And now that we've got the train shelves in the kitchen, you know, I could put a food themed railroad on the table there. Yes I already have the desert themed one in the train room and the prairie themed one in the living room and the snow theme layout in the hallway, but I don't have a silly one. No of course the Halloween theme one doesn't count.