Because that's his basement, where his hot water heater is surrounded by dirt where one could also assume the washing machine and clothes dryer is.

One the one hand, the scale of this dirt playground and expensive radio controlled cars would make any grown man weep for a chance to be 10 years old again. On the other hand, you have to hope that this much obsession for 100% perfectly-scaled realism isn't as creepy as it looks.

In any event, this is impressive.