Well you can buy assets and customize them. Swapping materials is easier than making entire asset from scratch.
I think the most valuable asset packs will be those, which allow for easy customization.
Let’s say rock pack. What are rocks everyone know. But if the assets in pack are thought of, you will be able to just swap some textures around just to get your own rocks, without trouble of making them from scratch.
Anyone who treied to make good looking rocks, know the pain of sculpting them and baking. But once you have that step done, you create endless variations by simply changing color textures.