I don't know how long we have to stay in the loop of this stable income in FR...can you possibly define the term stable income, Not everyone has a stable income and not every stable income will last forever.
You can start Bitcoin investment without a stable income and work towards getting a stable income (sure no doubt that a stable income can help ones investment), Besides it depends on what you define as stable income just as have said earlier, we all have a view of defining our stable income, what you call a stable income might not be stable to another person.
It seems that I also have to agree with what you say because there is an undeniable reality that the income that we consider stable is not considered stable by other people based on the definition. However, in general, stable income starts with income that is always regular every month, the amount of which is not too different between last month and this month.
And for the investment side of Bitcoin, I also have suggestions that are not much different from yours because basically everyone can invest in Bitcoin even if that person doesn't have a stable income because that person can still buy Bitcoin when they have a certain amount of money at a certain time. However, we also have to admit that people who have a stable income will find it much easier to invest as long as there is a strong intention to do so through Bitcoin.