I can boldly say that you are wrong here ensuring a stable source of income before starting investing is not a basic condition of Bitcoin investment, the basic condition is having a discretionary income, no doubt that having a stable source of income is good but it shouldn't be seen a basic condition before starting bitcon investment because there are those who's income source are not stable but yet they still buy Bitcoin whenever there money comes in like a contractor.
Income is very important to invest in bitcoin and how one is able to manage expensive and to manage investment is also important. For you to go into bitcoin investment it is good to have income that can make you to invest from time to time. One of the challenge of some people they are not consistent with their investment because they do not have income, some have but they have problem with managing their money and they struggle to invest bitcoin.