I agree with you, DCA is actually more beneficial for those who have limited income and can afford to invest small amounts of money, but the sad thing is that those who have such a small income, they are actually in the wrong mindset that they think that Bitcoin investment requires a lot of money, There is no profit in investing small amounts here, which is definitely a wrong mindset. and because of this they delay in investing in Bitcoin, which is definitely a wrong decision for them.
And yes, it is definitely true that you have to be consistent, no matter how much money you decide to invest, it is not a big deal, the most important thing is that you have to be consistent, and you have to continue this process for the long term. Only then will there be a chance of success from it, and for this, discretionary income is definitely the best option. People can create a discretionary income source with a little effort, all they need is real willpower.
I am sure everyone must be familiar with news that a Satoshi era investor has recently sold his 80k Bitcoin for 9 billion US dollars and the purchase price of these Bitcoin will be around 10$ per bitcoin or may be low. If anyone has invested few bucks in Satoshi era and still hodling it then imagine how much profit he is getting today.
I quoted this news just to give an idea that amount doesn't matter, what matters in Bitcoin is the time you are willing to hold. Keeping this thing in mind we must follow DCA for long term and that's why I say it doesn't matter how much you invest per week, important is you invest with consistency and for long term.