Asides the DCA, Bitcoin investment is for those with a steady paying job, not for people that wants to risk their cash to make quick money, someone without a job can't even hold for long cause they'll be forced to sell during time of emergencies, their only hope would be one their investment since they don't got other money therefore it's not advised and whether DCA or not an investor should have a job already.
The DCA method is not for only those with stead cashflow as I have been made to know by JayJuanGee when someone ask the question in early part of the thread. In his response, even though your cashflow is not regular, you can still figure out a way to invest using the DCA method and that can only require you taking average of how often you receive inflow and then make projections from there. You can be in a type of business that pays at least once in a quarter. You can do your calculations from there by first calculating what your basic needs would be for the quarter, then removing the amount for investment and even emergency funds and some reserve funds.
I agree with you that DCA strategy is not for only people that recieves steady income weekly or monthly, the most important thing is for you to have your means of income and discretionary income available. For instance, a contractor don't get paid weekly or monthly because he depends on getting contracts from companies or the government. Such investor can still use DCA to build and grow his bitcoin investment.
When the contractor gets paid, he will plan on how to manage his funds to sustain him for long before he gets another contract. He can reserve his discretionary income, because he does not want to lump sum all in once. He can divide that money into various weeks and spread them across, since he knows that DCA gives more opportunity to buy bitcoin at various price instead of lump sum. The contractor can also frontload his bitcoin investment.
What really matters as a bitcoin investor is for you to keep your bitcoin accumulation ongoing with persistent, consistent and aggressively overtime till you reach your bitcoin target and work on how to increase your income.