That mainly depends on what number of total bitcoins you hold in your account if the amount is good enough then definitely its an best option to opt for because the value of bitcoin will be more after 20 to 25 years so it would be best to have bitcoin as a retirement account.
Actually it doesnt matter how many bitcoin that you got in total. If you want to really use it for retirement account and you want to get some profit with it what you must do is start to collecting bitcoin with all the money you got now since the price is still low