The goal of the modern DNC is just enough majority to gain control, but not enough that voters would call for them to actually fix the things their donors like broken.
Because that involves losing House/Senate seats in "red states" they've just abandoned them.
Things like the "victory fund" exacerbate because what little is turned back over to states, is usually days before the election when it's hard to be utilized or even after the election.
Because the max state donations are being routed straight to the presidential candidate, it also dries up available contributions directly to a state.