I work in tech, and I don't understand people's obsession with having all their RAM free at all times.
If you don't use it, why do you have it?
Windows (not the best OS, but the one I know the most about), will lie to you about how much memory you have that's free. It puts data in RAM as cache. In the event you need that data, it's already loaded in RAM. Usually this is stuff like DLLs and executables for programs.
There's a difference between "free" memory, and "available" memory.
In addition, RAM is always going down in price, so 32G today costs what 16G did, some number of years ago. The same can be said for 16G vs 8G, etc. Though, the comparison becomes less relevant as you get into much smaller and older memory types, since the cost per dimm will only ever go so low.
Buy the memory, use as much of it as you can, as often as you can. Go wild with it. Enjoy.