I agree with @sticky bomb, because someone may not have steady source of income but can have a discretionary income from his or her source of income. People with this mentality that someone need to have a steady source of income before the person can start investing in bitcoin are getting it wrongly, because what you need to start investing in bitcoin is you discretionary income , as in a left over money after you must have settled your needs and expenses either for week or for the month. If you can be able to make your discretionary income available from your main source of income then you can start investing in bitcoin with consistently with commitment and building up your emergency fund and your back up funds alongside your bitcoin investment.
It's important to invest in Bitcoin, especially if you are aware of what benefit you will get by investing in Bitcoin. Those who have discretionary income should invest that in bitcoin without giving it a second thought. Those who don't have any spare money should start thinking about how they can generate additional income that they can invest in Bitcoin. These days their are lots of options available which you can avail to earn money. It's upto a person that how much he is enthusiastic about investing in Bitcoin. If he is committed, then he will eventually find ways of investing in bitcoin.