well for me bitcoin is not a bad idea when you're retired after all.so better save your money for the future.i continue the bitcoin because there's a chance that migth bitcoin can grow more than spent my retirement money for vacation.
The comparison you make is bad - you are talking about investing your retirement money in bitcoin rather than spending your retirement money on vacation. The problem is - you shouldn't be spending your retirement money on a vacation in any case. Personally, I would be comfortable only with investing a small amount of my retirement fund in Bitcoin.