I do not know if there are actually a lot of people trying to use bitcoin as a way to save for their retirement, but I think it is a good tool for this goal in particular, as even if bitcoin is relatively young compared to other popular investing tools, this also gives bitcoin the advantage that it can produce much higher profits compared to them, so as long as you begin to invest all the money you can in bitcoin, and you can keep holding it until you reach your retirement age, then you will have way more money than other people that did not took the time to invest or that did so in other assets.