Is paying $1-3 simply for a click on google ads worth it either?

(In my experience, no).

I don’t have experience but I thought Subprime Attention Crisis was an interesting read

Yep, and what your CPA is.

LTV for a 30 yr mortgage is hundreds of thousands - that pushes for some expensive clicks at auction.

To the users who have actively indicated that they are interested in downloading your app, all at the same time on launch day, potentially putting you on some "most downloaded apps" leaderboards? Quite possibly, yes. It'd depend a lot on the app, though.