You are repeating the same thing over and over again. Buying on Lump sum is not a do or die thing. Everyone should cut their coat according to their size. If you have to lump sum then do it if you don't have then go with DCA. Smaller investors should use a strategy that suits their financial capability and leave huge investors to lump sum.
I believe that smaller investor you mean are those that don't have a larger amount to accumulate with the lump sum strategy I don't think there is anything such as smaller or huge investor people on accumulating bitcoin according to the level of their discretionary income but why the DCA strategy is mostly adopted is that it gives investor the opportunity to accumulate Bitcoin gradually increasing their bitcoin stack either weekly or monthly and also choose to lump sum if the money is there investor who have money to lump sum can also use the lump sum strategy if probably he won a lottery or got an extra income from place of may also decide to lump sum and still be doing the DCA strategy also, so the lump sum strategy is not only for the rich investors.