The only challenge that someone using DCA method is when the source of income is not steady
This was my thinking too and I even made a comment referencing an entrepreneur. Thankfully, JJG explained convincingly, how this can be achieved. From that explanation, you can actually know your financial inflow within a certain period like a year, from that you can know what to set aside and plan your DCA accordingly. You must not be earning fixed income monthly or weakly before you can perform DCA, even when your inflow is not regular, you can take average with a time period and as soon as you have any bulk funds, you can start off with the part that fits into the average you have worked out already and because it is exhausted, you would have receieved another inflow base on your calculations.
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.