My house had a built in 8 person hot tub when I bought it.
Not sure of gallons but it seated 6 really comfortably and could really do 8.
I ran the heater timer every other day for one hour.
If I wanted to use it, I had to wait another hour for it to get to temp.
(2 hours on the off days).
I used it maybe one or twice a week.
It doubled my electric bill and trippled my water bill.
It started developing bubbles in the fiberglass.
I fixed it twice and then just quit dealing with it.
Now I use the circuit and part of the wiring for my garage power.
I'll be ripping out the carcass and filling in the hole soon.
Oh, almost forgot the knife edge pH requirements.
I can't imagine going through that on the scale of a full size pool.
My wife has said in the past that she wants a pool, and I've always said, sure, but you get to maintain it and pay the difference in the utility bills.