Pension plans are not good enough I guess. They don't pay a high rate of returns and you also have to pay the premium monthly or yearly depending upon the plan but If you hold good amount of bitcoin then it can proved to be a good investment option at the retiring age and you can sell bitcoins anytime you wish its not compulsory that you have to wait till you get retired 
Pensioners are getting a raw deal in the recent times, in many parts of the word. Take Greece for example. The government has severely reduced the pension payments, in order to obey the terms of the austerity measures. Imagine someone who has contributed to his pension fund for 30 or 40 years suddenly waking up, to find that 90% of the funds are gone.