I happen to like a small house but 100 square feet is overdoing it. My dogs and I would be fine with 5 or 6 hundred square feet.
If I could get away with it I’d take half my garage in make it into a home.
I have to admit that this sort of thing intrigues me. But more from a “man cave” perspective than anything else. There’s one guy in NYC who actually took a dumpster (brand new and unused one) and turned it into a house complete with an attached gas grill, “roof top” deck, etc.
Many years down the road, when the kids are out of the nest and the wife has taken off with the mailman, a small house like one of these on a small river with a dock for a 25’-28’ sailboat would be my optimal retirement pad.