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I think what people fear is volatility of Bitcoin. We have seen its value fluctuate in the last couple of weeks in significant amounts. But keep in mind that Bitcoin has gone a long way from the moment it was introduced. So it is really just a matter of taking risks and believing in bitcoin.
I can say that what mostly people fear about bitcoin is that the fact that it will get lost or maybe end or the service will die. Theses past few days, bitcoin has been inconsistent about it's price. It moves suddenly then stops. And because as of now many people are happy with bitcoin's service. It also helps a lot to get an earning for living.