You have a good point but you are a bit confused or lack some right description of what you meant. The idea of DCA strategy doesn't make investing in bitcoin and expensive venture, infact, it makes it much easier to accumulate more bitcoin with less financial stress. DCA approach works best together with Discretionary income. Anyone that invests more than his stable income is either greedy or uninformed. It is not even advisable to invest all of your stable income into bitcoin to avoid stress. Emergency funds and backup funds are the key strength of holding your bitcoin stash. So you make provision for emergency funds and back up funds before investing in bitcoin. Emergency funds have no fixed amount, you only envisage what could sustain the period before your next income and then what is left is what you can willingly invest in bitcoin.
What exactly are you even saying here? Every other strategies or infact Bitcoin investment requires or works best with a discretionary income the reason being that that is the only way we can be investing and at the same time be taken care of other important needs without struggling, whichever strategy or of accumulation we are using be it Lump sum, DCA or buying the dip the investment money must be a discretionary income if not you are gambling rather than investing, my point is that our investment money should always come from the angle of a discretionary income meaning that you are not investing most or all of your income in to Bitcoin but just a Left over cash after ensuring that whatever that is considered to be your basic needs has already been taken care of.
Honestly, you gotta take care of your basic needs first before investing. Use the money you can afford to spare, not the money for rent or food. That way, you can invest without stressing about your daily needs. You'll be more calm and make better decisions.
A person needs to get their essential needs met first before they should invest that's why using their discretionary income is the best advised. It gives you financial stability and reduces stress because you have other needs tackled already and so you won't have anything to worry about or every think of going back to your investment or relying on it to survive.
Investing discretionary income is a responsible and sustainable approach to invest if you don't want to jeopardize the success of your investment because it ensure your basic needs are met.