You're right for the fact that One chooses to invest in bitcoin using the DCA method does not mean that he/she does not have enough money to buy in bulk, of course if it is your first time of investing in bitcoin you will always want to play safe because is your first time of investing so you will always want to go with the amount you can easily afford so that even when you experience lose in the market is not going to affect you in anyway. I'm pretty sure that anyone who's new in this crypto space will always want to do the same, you can decide to buy in bulk when you finally understand how the market works.
Buying Bitcoin in large amounts and also in small amounts is actually still not much different even though the amount is very different. But for investors who always target big profits in the long term through Bitcoin investment, of course they will use every method that they think is still comfortable enough which generally will not interfere with their own living conditions from day to day.
In addition, investors must also have a higher level of patience in maintaining the investment assets that they have purchased without having the thought of immediately releasing the assets when there is an increase in price or correction in the price of Bitcoin which might cause panic in their own minds. Because every investor must have the goal of buying more than selling, certain methods such as DCA can still be used to support their own plans.