That's one type of kid.

I have an acquaintance who borrowed someone's goat for a few months to deal with her grass. Unfortunately, she also had a deck that surrounded a portion of her house. The goat destroyed[1] the deck (and I believe a portion of the siding). Having a relatively large animal (for a house) with hooves running (galloping) around on a wood structure isn't necessarily a good plan if you care about that structure.

1: Well, maybe not destroyed. Achieved the equivalent of 10-20 years of normal wear in months may be more appropriate.

Children have also historically been an insurance policy. Should you have financial or medical hardships later, they are generally more likely to have your best interest at heart (however they perceive it) than some disinterested third party.

Brush fires.