CAP is cheaper ($70 wet for proficiency in a nice 172, typically), but you need a certain amount of hours to qualify to fly for them (if I recall correctly). It's a great way to stay in the air, though - even if you don't act as PIC, you can fly as an observer.
As far as having to take a checkride if you lapse, that's basically only true for the instrument rating. For the private, the BFR is as much brushing up time as you need to be safe in the air again.
I hadn't flown since 9/11 (yes, THAT 9/11 - I was making instrument approaches in North Jersey at 0800 - but that's a different story) until my recent BFR (airport closed, needed the money, had another kid, finished a PhD - got too busy and poor for a bit). When my BFR was due, I read a ton and did alot of mental practice - then did ground and a LONG 3 hour flight. Kind of like riding a bike - it all came back and I got my sign off. NB - I WILL NOT TAKE PASSENGERS UNTIL I GET MORE HOURS (prolly a few more with an instructor even). So, no, letting skills lapse doesn't mean loosing them (though I echo the IFR sentiments). Only you know just what it'll take to keep SAFE (as opposed to legal).
As far as borrowing money to fly, that was mostly tongue in cheek. Although..... 😉
GAWD, I love to fly.
Keep the shiny side up,
P