Ram is like food. If you don't have enough then it causes problems, but if you have too much, then a bunch of it simply goes unused.
If you are doing web browsing and video games, then 4GB is sometimes not quite enough, and 8GB is plenty (at least for the next few years). If you are doing a lot of multi-tasking, or light to moderate content production then 8GB may not quite be enough, but 16GB is generally plenty. If you are doing a lot of production work every day then 32GB is generally going to be plenty, but 64-512GB of ram is not unheard of.
So how much do you need? Open up your web browser with a bunch of websites. Open up a few office documents, a media player, and a few utilities. If you are doing editing then open up...