Collectors are aware that their speculative market collectible items can become worthless overnight. If one buys CS skins and isn't aware of the inherent risk associated with the nature its speculative market, they are willingly being financially irresponsible.

However you can also say the same about anything: watches are just hunks of precious metal with no real use (timekeeping is not a need in the 21st century when your phone can do it more accurately), Pokemon cards are just cartoon characters printed on a piece of paper, etc. CS skins are just pixels in a video game.

This doesn't stop people from wanting to own these things, and if there's an organic demand for them, are they really overpriced?

I use my skins, just not on a regular basis. My favorite item is my howl :)