I personally believe that Bitcoin now is reaching a stage where more and more lay people are interested in earning it and also holding it like an investment, as they would hold metals and bullion. I think it is here to stay for a few generations at least.
It seems that it might be increasing in price. Keeping Bitcoin as a investment might not be a good idea, though holding at least a single Bitcoin could be a wise choice.
If nobody would invest in it and we all would just buy 1BTC and held it there, it would die the next second. In order to increase the price, we need to use it. We have to show that we're interested in it, and the price will increase. Investing in anything can be a bad idea, not just Bitcoin. It's all about the luck you've got. You can turn your small investment into hundreds of thousands if that's what you deserved.
It not all about luck, but about how useful and solid your investment is, right now bitcoin seem pretty solid to me are there risk? Yes, but the same can be said about anything.