For me, no amount of bitcoin is enough to secure future. Though as what's happening now that somehow make bitcoin stable in long run, we can't still deny that there is still a chance for bitcoin to fall. Lucky, if after bitcoin crash a huge percentage the person who buy bitcoin as retirement fund can wait until bitcoin recover and raise again but what if not? Bitcoin is a great investment but just like most investment crypto or not the profitability pecentage is not always 100%.