Best money I ever spent

Easily.
This summer is the 5th year anniversary of us putting in our pool and it is by far my best purchase ever.
We don't have a cottage and despite renting one for a week each year our backyard is where we spend most of our summer days.
When we dug the hole my kids were 5 and 8 and for the first couple of summers, all day ever day, all we did was swim together.
While my wife watched of course. The set of circumstances that will get her to actually enter the water, are so complex and diverse that they really only occur a couple of times a year. She does love to lounge though.
The girls and I love to swim. And throw a football. Or whack each other with pool-noodles. Or try and find things on the bottom. Or pretend to throw their mother in.

Even now that they are 5 years older we still spend a lot of time in the pool...together.
That's why it's been such a great investment. For many summers, I have spent an inordinate amount of time within a few swim-strokes away from my kids.
I wouldn't have missed this for anything.