Not having a steady source of income shouldn't be a hindrance for investing in bitcoin so from you are saying, even if one has a discretionary income so long as they don't have steady source of income they can't invest in bitcoin. This is wrong, because one can be investing in bitcoin using discretionary income while working to stabilise there income. So to me the most important thing is if the person has a discretionary income to invest with and as time goes by , stabilise his income
I am very confused after your comment. Because you are making the two types of income very complicated. For example, discretionary income is the amount of money that you have left after deducting all your expenses. You have a source of income from where you get a salary or daily income. The amount of money that you have left after deducting all your expenses from your money is discretionary income.
What you have highlighted in your comment is that you have to work separately for discretionary income and you have to work separately for stable income. But actually, that is not the case, the amount of money that you have left after deducting all your expenses from your stable income is discretionary income.