By definition, you need to have either income or some side amount of savings (or other investment) that is greater than your expenses in order to be able to invest. If you do not have excess, then you are gambling rather than investing.
Of course, you could also invest if you don't have extra income but you are expecting your income to increase, but that would be a bit risky also, or you can invest based on future income that would be considered a loan, which is also risky and problematic if you don't already have funds to be able to service the loan and strong chances that your future income is not going to dry up.
If you are using the anticipation of paying the loan from the appreciation of the asset that you are buying, then you are gambling.. which may well be ok. if you have back up funds to service the loan, otherwise if you don't then you are likely taking excessive risk, which is also gambling. Sure people can do whatever they want, and sometimes gambling techniques work, but each of us should be careful if we are employing techniques that might be difficult to recover from if the price were to move against us or other unexpected things happen to cause us to lose our principle.
Of course, passive income will launch a DCA investment process in accumulating Bitcoin. Many people in the world may not have a permanent job but they want to invest and maybe it is a long process for them to have a certain amount of BTC. Yes, we encourage anyone who is confident in investing in Bitcoin to do it using DCA because they need to arrange their entry in such a way to find the lowest price. So back to the issue of income, investment can run smoothly if someone earns passive income every month so he is not burdened by the circumstances of the investment he makes.
Apart from that, Bitcoin has become an investment that is attracting quite a lot of attention at the moment. I noticed a lot of newbies keep coming in to buy bitcoins and hold them. Yes it's an extraordinary process of their desire to achieve success in bitcoin investment. However, from that perspective, we certainly don't know their principles in balancing their financial cash, but of course they have arranged it as best as possible so that the Bitcoin accumulation target can run smoothly according to their planning.