This is retarded. Bitcoin can't replace stock MARKETS. A market is where people go to exchange.
Bitcoin can't, no. But I'm not talking about bitcoin. But you are forgetting that the blockchain - the protocol - is like HTTP back in the early 90s, a foundation layer upon which nearly anything you can think of can be built.
It's like saying, "this is retarded, you can't replace MONEY with HTTP, you need MONEY to pay for the servers which HOST the internet!"
And yet, without the advent of HTTP two decades ago, there would be no blockchain today. Get it?
If not, read
Bit-therium.