Steam is accepting the bitcoin and that is not really known these days so that is pretty funny, the prices here on the forum are also much better so its logical that it will not really affect the market right now.
What price here on forum are you talking about? People selling games/keys on digital goods?
I think you can save more with steam discounts and promotions.
Steam is still very high with their prices compared with as a example G2A, I think that the market did not change and I agree with the person that its cheaper here on the forums than on steam itself!!
I took a look and well, don't look secure for me, if the guy sold the key for me, for sure he can sell to other person the same one... And by the way sounds like a black market with a lot of hacked accounts, we can see people selling everything there...
I prefer to buy on steam...