Thats right.
Those who has a lot of btc should put some of them into the market we need to build, even if it doesn't pay off right away
Nope. If people buy up all the shares of a company or all the gold or whatever, it doesn't make them worthless; it makes them rarer and therefore worth more. Bitcoin, like anything, only gets its value from what people are prepared to pay for it. And people are still buying and selling Bitcoin. Sure, there's more and more hoarders everyday, but Bitcoins are constantly coming into circulation via mining and those miners need to eat and pay their electric bills. Scarcity only pushes the value of something up and there will always be people who decide to capitalise on this and sell their coins.
BTC is a currency after all, you are free to buy, sell, trade or save. Completely up to you.