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.
If we look at it basically, every investor must have an income to be able to invest in anything including Bitcoin because it has become a fairly basic foundation for all investors. Regardless of whether they have a stable income or not, income must still be there to be able to start investing in Bitcoin because the basic action of investors is to buy Bitcoin with the amount of funds they have. As for how to manage it yourself, I think it is more about each individual's strategy because as long as the intention to buy Bitcoin is still in their own heart, of course it will be done very wisely without looking at more suggestions that might make them dizzy.
When an investor has a certain source of income but at the end of a certain period of time he can earn a good amount of money from that source of income and when he has income but he can spend and spend the remaining money in Bitcoin. Assuming an investor has some amount of money saved and outside of that savings, that investor has no separate source of income, then it can be seen that if he starts investing in that situation, he can continue to invest as long as he has that saved money. But if the investor has a source of regular income instead of having savings then he can maintain the continuity of his investment for a long time.
So it is very important that the investor has a source of income.