For some people there may be those who invest without capital, but for others or most people the main requirement is capital, on the contrary I have not found people who invest without capital, in my opinion, I do not agree with the absence of capital, because the slightest thing, the will or desire of a person can be said to be capital, to be confident.
As long as you have an income, you have capital to invest in bitcoin. Your problem is, you see capital as a special fund that is either outsourced or saved for a long time. Capital is simply money you can use to invest and with bitcoin you can invest with whatever you have.
If yo have an income. The smaller your income, the smaller your investment might be.
Imagine having savings and saying you're waiting for capital to invest in bitcoin. It doesn't make sense because that savings can be your investment. It can be $20, but as long as that $20 can grow to $25 or drop to $15, that's an investment and that's how it is with bitcoin.
As long as you have an income, you have capital to invest in bitcoin in my opinion.