I don't think the profit from investment can be a stable income, because you can't guarantee that the profit will always come from where you invested. Because in investing, there are both profit and loss.
Rather, you can do this whether you are stable or not, when you have an opportunity to earn a part of the money you earn when you have some money left after meeting all your needs, you can invest in Bitcoin.
For example, suppose this week you have $ 100 left after excluding all your expenses (primary needs + emergency funds), you can invest it in Bitcoin for the week.
Again, if you have no money left after excluding your primary needs and emergency funds in the next week, you don't need to invest in Bitcoin for that week.
Again, suppose next week you have $ 50 left after meeting all your expenses, you can hire Bitcoin AB.
The point is like this, investment is not a job that can generate regular money every month, but investment is a way for us to make the money we have stable in value and so that our money increases. What I understand so far is that investment is like that concept, whether it is in bitcoin or in other assets. Then talking about investments that can generate passive income, of course there are such investments. For example, if we buy shares in a restaurant, clothing store, or nightclub. Of course we have the right and share to get profit, from the turnover of the places where we buy shares. But if we talk about investing in bitcoin, I think it is difficult for us to get passive income from bitcoin, because bitcoin is really an absolute investment asset like gold. So bitcoin is really a long-term investment asset. Therefore, if we want to have a stable income, we must have a business and not just rely on investment.