IDK why there has to be something deeper.

>public park's pristine full-courts

I mean there's only so many courts maybe you don't want to play with other people you just want to take shots, and it's convenient.

>Neither does it shed any light on the sad way in which suburban dads build rickety basement bars

They do it to hang out with their friends. Same way you order a pizza and eat it at home instead of at the restaurant. What are you after the pizza or "being at a restaurant". For most people it's the pizza. The phenomenon of rickety basement bars as you call them is just people hanging out at home drinking cheaper beer at a home built bar. They get some of that "I'm out of the house" vibe while getting all the "hanging out with my friends" that they really want.

I don't know what else you are implying could be operating here. So I'll have to assume you just hate improvised home bars.