Apparently, there is no investment without risk or in your words risk-free investment because as long as investment is concerned there is some kind of risk attached to it. it's either one is ignorant of it or intentionally ignored the obvious signs of risk but basically in bitcoin investment we are only on a better angle of not gambling our investments but staking it for the future which we are guaranteed for with the four years circle that we know.

Since investments are of risk, bitcoin invest too is full of risk such as wallet security etc.