I think Bitcoin is the quintessential investment for retirement.
Keep your job, save to invest and watch it grow. Obviously you need to have more than just a couple of Bitcoins in order to be able to live through your old age. My advice would be to never keep all eggs in one basket since no investment is ever 100% risk-free.
If you are able to collect some coins at a good price then it will be useful as the price might reach astronomical figures five years from now and if there are other opportunities to maximize your profit as there are new promising crowd funds that would double your money within a few months and so i am hopeful that i could make a good money before retirement.