[2021] Why does this game eat my ram so much?

Loading the map is using so much ram. Unlike GTA which constantly loads and unloads play area, in 7DTD the entire map is loaded in with a lightly initialized state the start, and made active as you travel around and explore.

You might also have some of your video settings too high and have vRam stuff dumping over to normal ram. Textures especially will eat your vram, if you have it on full that alone is 8gb vram i think. This would definitely cause performance drops if its happening.