for the sake of old age insurance then we can work in the real world (work offline) but By looking for Bitcoin you can also open old-age insurance(Independently)
If we are talkinh that you are in the age where you have enough energy to do both then why not since it is not a matter of earning more but to stay in a safe side and balace it out with volatility in bitcoin and stability in your job in real world.
If your old or just enough where you wish to retire and your children had finished their studies then you can treat Bitcoin as a retirement work or qhatever you call it.