If a person has a reasonable source of income and is willing to invest, then he should never delay investing. It is best to start investing first. You can do everything after investing. If you want to learn everything beforehand, then it will be too late to invest, it will never be the right decision. You have to start investing first and then you can learn a lot.
I don't think an investor needs a reasonable source of income to start investing in bitcoin, what an investor needs in other to start investing consistently is a discretionary funds, because their are so many folks out there that are earning quite a lot of money or a reasonable source of income as you claim that still can't invest in bitcoin because they they can't sorts out their discretionary funds, so in my own opinion, what a newbies investor needs in other to start investing in bitcoin is discretionary funds and the basic knowledge on Bitcoin and how to go about your Bitcoin investment.
There is a big difference between reasonable income and discretionary income. The type of income source or the amount of income does not play a significant role in investing. The most important thing is whether the income source can provide you with discretionary money. Even if your income is $10k per month, it will not be suitable for investment if you do not get discretionary money from it. An income source that goes to $1k per month can also be suitable for investment, if it is possible to select discretionary money. That is, the expenditure based on your income will depend on whether your income source is suitable for investment or not. In some places, even though you get high salaries, it becomes difficult to set aside discretionary money due to inflation there. In some places, even though you get low salaries, it is easy to get discretionary money because there is no effect of inflation. This varies from place to place. So, instead of giving importance to the source of income for investment, give importance to the source of discretionary income.
This is actually a solid point Jewan420, and I think one angle people sometimes overlook is the psychology tied to discretionary income… It is not just about whether you have leftover cash, but also how disciplined you are with that money.. Some people make good salaries / income why ever you call it, and still feel broke because every little extra they have, they find a way to spend it.. Others who earn much less manage to build their Bitcoin holdings simply because they understand how to prioritize, cut back on lifestyle inflation (yes lifestyle has inflation, bcus the more you earn, you tend to increase ur style of living), and direct that leftover money into long term investments like Bitcoin.. So, in that sense, discretionary income is less about the numbers and more about mindset and self control. Even in high inflation places, some people still manage to make out discretionary money because they treat investing as non negotiable, almost like another bill they have to pay..
Another angle I see is that discretionary income also reflects opportunity cost. For example, two people might both have $500 left after expenses, but one sees that $500 as extra to spend, while the other sees it as seed capital for their Bitcoin future.. The way you frame your discretionary money determines whether it builds you or just disappears. That is why I feel the key is not only about having discretionary income, it is about what role you assign to it in your life.. If you see it as just casual spending money, you will always miss the chance to grow your portfolio. But if you dedicate it into something like Bitcoin with a long mindset, it would pay off.. So yes, the source of discretionary income matters, but the intention behind how you treat it might actually be the biggest difference..