Most investments are risky, so Bitcoin is not the most risky investment. In the early days of Bitcoin, I did not buy tho but I want to believe that its acceptance would not be easy however, the people that believed in it faced it head-on and some got the dividend because nobody can ascertain when BTC will be at its maximum.
The most risky IMO is the crowdfunding created by random developers. They just come out of no where, propose an idea and ask people to fund it without giving their identities. I find it very risky because there is no assurance that the project will commence after gathering the needed money. There are lots of this kind of case happened in the previous year and it still come popping out every now and then.
Though investments always have risks, we should learn how to manage risks by knowing the important factors to check in order to avoid unnecessary risks. I would not deny that Bitcoin in its early years can be labeled a high-risk investment but as the market foundation becomes more stable, the risk coming from Bitcoin investment becomes lesser and lesser.