All they need is discretionary funds.. which means that it is funds that are extra after they have accounted for their expenses.
The only difference with my use of the term "income" is to suggest that there is a steady flow of discretionary income every week or every month, and in order to invest into bitcoin you do not need a steady flow of income.
As far as I can understand from your post, the mistake we often make is that we consider discretionary income in investment, but if we look deeply into the matter, we can see that there is a slight difference that would be discretionary fund. By discretionary income we mean the income that a person receives consistently like weekly or monthly. But when we say discretionary fund, it is an amount after spending all expanses. It can be 10 dollars or 20, any number, and in the case of investing in Bitcoin, we can invest that amount. Discretionary funds can be said to be money that I have no obligation to use. I can spend it wherever I want, according to my wishes, and that money is worthy for Bitcoin investment.
There is probably no need to get overly caught up on the difference in the terms, yet when guys are proclaiming that there is a need for a steady income before getting started with investing into bitcoin they are wrong.
Sure it is nice to have an income flow and a good job and even a lot of discretionary income, and that will help guys to buy more bitcoin and to create stronger back up fund systems.
Yet no one is precluded from getting started investing into bitcoin merely because he does not have a steady income... . and he is also not precluded from continuing to invest whenever he has discretionary funds.
There may well be cases that the discretionary funds are not enough and the future employment and the future income are too uncertain to be able to invest into bitcoin, and each person needs to make those kinds of judgements, even though guys continue to be wrong to repeatedly proclaim that guys need to have a steady income before getting started investing into bitcoin.
The most important thing is that we get started as soon as possible irrespective of how our income flow is, and along side our bitcoin investment we should also provide means for back up fund for emergency situations, so we don't go running into our bitcoin investment when we encounter situations that demand immediate intervention financially. It's a plus up to have a steady paying source of income or a good paying job, so that our discretionary income will be frequent so we can just follow a schedule for each month or week but if that's not the case then there's no need to feel inferior because bitcoin investment isn't limited to only a certain kind of people, it's for all and can be better achieved when you put the concept of emergency funds and reserved fund alongside your bitcoin investment, though it may take a while to build even for a year or 2. But the most important thing is that you have it aside and build your bitcoin portfolio.