why are skins for guns so expensive

CS:GO one of the most popular FPS game

I guess it's because they gotta make money somehow. But the skins don't really change the gameplay, do they?

they need money as cs go is now free on steam

i dont know ask valve why lul

This is how business works in real life:

More people own it = Lower price
Fewer people own it = Higher price

That's because nobody will buy 100€ skin if they can buy it for 1€. But if just 1 person owns the skin you either pay 100€ or you don't have it. Now there are 99 more people who have the same skin. They sell it for 50€. So nobody will buy yours for 100€ if they can buy it for 50€. You want to sell the skin so you lower your price to 40€. And it goes on and on.

because if all of them would be available for cheap, there won't be sense to buy them at all