It is very normal to have doubts about investing. But based from your experience, you should have learned your lesson already. Neglect your doubts and buy some Bitcoins now. I repeat, NOW. Yes bitcoin is uncertain due to its volatility but that is the best part, you might have 50%-100% profit within just months. Do not pay attention to those who claims that Bitcoin will bite the dust and become worthless just because of an alt coin. So buy now and suffer from disappointment again. It's your call.