Regarding where Bloomberg et al could've better directed $ -- was looking at this Houston suburban race between a GOP sheriff, and Indo-American who was reaching out to diverse Asian communities. Asians, statistically, have voted less, and he tried to reach out and motivate them. Some groups under that broad umbrella term vote on whoever supports small businesses, and respond to GOP candidates on reducing government, some, like Vietnamese, are intensely anti communist and respond to red-baiting "Socialism! " cries. Etc. So the Indian is pitted against a guy who, a couple years back, tried to prosecute a driver for having an anti Trump bumper sticker, which would seem like all any sane person would need to know. OK, that Indian guy could have used the money to better penetrate the electorate with information on how he would support small businesses, help them through covid times, and on how his opponent is essentially a fascist who would deny people 1st Amendment rights.
Just one example. When people undervote, as happened in some places with Biden, that can hurt House candidates who may be more aligned with Biden.