Yeah, DCA can be very convenient for both rich and poor but I think it's not really the most convenient way to increase ones Bitcoin but rather it depends on the investor's capacity or level of income. Those investors who uses the long sum strategy may/can not consider this strategy because DCA is a gradual way of acculturating Bitcoin therefore a lot of consistency and discipline is required or needed in other to achieve the goal.
You should change your negative thinking about DCA procedure.
One of the biggest benefits of investing in the DCA method is to minimize the volatility of the Bitcoin price and try to stabilize it. Although it is not possible to completely stabilize, most unstable conditions are reduced. There is a clear understanding in your words, where you try to say that the DCA system is more favorable to the poor. But you will be surprised to know that some of the most popular companies in the world invest in Bitcoin through the DCA method. One of the best companies in the world, MicroStrategy, Tesla, Square, Galaxy Digital and many other companies invest in Bitcoin using the DCA method. They have become whale investors by adopting the DCA method. The DCA method is equally beneficial for both the rich and the poor and it would not be wrong to consider this method as the best method for growing Bitcoins as well.