Not everyone's income is the same. There are many people who work as daily wage earners. For example, after working all day, they are given a certain amount of money as salary, they can continue to buy continuously by adopting the DCA method every day. This will not be bad at all. Because all the people who work as daily wage earners cannot accumulate or save much money. Because they have daily income and they spend almost the entire amount of money from it, so if they want to buy daily by adopting the DCA method, then it is not a bad idea at all.
I don't like the idea of purchasing bitcoin daily, especially when the person is not rich. Only a rich investor can buy bitcoin daily based on his cash inflow is large daily. Like the person that you mentioned in your post above should not buy bitcoin daily because his discretionary income will be very little since you said when he gets paid, he spends almost the entire money to take care of his daily needs.
It's better that such a person should pile up his little discretionary income for one week and buy bitcoin weekly. This will save him from the stress of buying everyday. If it's someone that lacks discipline on keep money for long, he can give the money to someone he trusts to keep it for him till the week comes to an end.