I dont think bitcoin will increase its value forever. It will follow the supply and demand law. Bitcoin is like a stock market but it is more risky than those on stock market but you may gain a higher profit on this. It will always fluctuate as we experiencing right now but it wont go low as much as $100 per bitcoin because there are many number holders of bitcoin value than exchanging or trading for pursue in money. I think it will not increase forever but soon it will stabilize its value