Cosmetic, not pay-to-win
CS2 skins change how a weapon looks but never affect gameplay. They exist purely as collectibles and status items, which is exactly why a real economy formed around them.
How you get them
Skins drop randomly after matches, come from opening cases (with a key), or are bought/traded on marketplaces like skin1. Rare patterns and low float copies command large premiums.
Why they have value
Scarcity (discontinued cases, special patterns), float (wear), stickers, and pure demand. A marketplace reference price reflects the lowest current ask across the market.