No one can earn a living by just holding his bitcoins because for earning a living someone surely needs a lot of bitcoins on daily or weekly basis so for that holding wont work as holding them for one week for give much profit always.
It's one of my point. You can't do now your favorite holding the coins for price increase because you really need to convert your bitcoin in regular basis. All your main spendings will now be shouldered by your bitcoin earnings so whatever the currenct exchange rate, you are force to withdraw some of your saved bitcoins to be used in your daily spendings.
So still it's better if you have another source to support your daily needs and let just bitcoin saved in your wallet.
Its good to earn stable income from full time job and invest some money in trading bitcoins from where you can grow your coins on regular basis and if you combine earnings from both then you can earn a good living.