I like to think about the non-steady income in a couple of parts.
The first part is just figuring out what is your worst-case scenarios, what are your best case scenarios and what is your average... So then with that information you can try to project ahead, and most likely mostly using some combination of the worst-case scenarios and the average in order to figure out how much money you need to keep in your emergency fund in order to cover those situations in which the worst-case scenarios ended up playing out rather than the average case scenarios.
So, even though not necessarily likely worst-case scenarios could end up playing out for 6-12 months or more, and so the emergency cash fund should be able to cover the gap between what you need to live and what kind of income is coming in. Hopefully, you are already spending (your monthly expenses) somewhere less than your average case scenario which should then cause for an ability to invest (or DCA) with part of the amount that you are living below your average case scenario. and sure if the worse case scenario persists for a long time, you may well end up needing to either reduce or eliminate your DCA purchases of bitcoin, but if you have planned in advance you should not necessarily need to stop your DCA, and for sure, you do not want to end up putting yourself in a position in which you end up having to sell any of your BTC during periods in which worse case scenarios are playing out.. which likely would mean that you had not sufficiently prepared in terms of your emergency fund and/or the ways that you had been choosing to live in order to make sure that you are generally living below the amount of your average case scenarios rather than spending more than that.
Another factor can be based on the increase in price of goods and services in a country, whereby the persons salary no longer meets the requirements of the things that is needed to sustain one's self. I think that have enough effect to alter one's DCAing in accumulating Bitcoin
That does not really change anything that I say.. if the change comes from changes in income or changes in expenses, there still are likely going to be needs to reassess from time to time, and some people still are going to have much more steady income as compared with others, and some people might have erratic extremes that cause their worse case scenarios to be $0.. and maybe they are always living on the edge too.. so they are barely able to meet their monthly expenses, and maybe some of those people should not be investing into bitcoin (even though the choice is theirs to make, but sometimes people make bad choices that amount to gambling, but they believe that they are investing.. but they do not really have enough of a cash flow or even an emergency fund to be in a position to be able to invest anything, but sometimes they still will invest and their choice to invest might end up being the wrong decision, even though everyone is free to make their own decisions, even when they make bad decisions and believe that they are working to make themselves better when they are not).
I see the points you are making, also same reason why most people sells of there investment because they have no left over money to carry out some expenses or emergencies . The best way they think of is to sell out there investment which is not helping due to wrong decision at the very beginning