Bernie Sanders, seven other senators urge Democrats to break with billionaire donors

If you take the numbers for spending and just look at competitive elections, the correlation is very weak if non-existent. Harris and Clinton both outspent trump and yet lost their elections.

More money tends to be spent on individual competitive elections, but the spending on competitive elections is not correlated well with winning, and there are way more safe elections than there are competitive elections. So more money tends to get spent over all across the many safe elections than on the few competitive, and very few donations go to the unfavored candidates in safe elections. Creating the illusion that higher spending correlates with success.

Ultimately the money flows to those liable to win because that is the best spend per dollar for someone trying to buy influence. And those safe seats need lots of money for their campaigns as a way to reward to those who have worked for them, but can’t be guaranteed further promotion do to a lack of opportunities. The rewards being things like lucrative consultant positions.

Correlation is not causation though. Better and more popular candidates are naturally going to attract more donations. Especially the corrupt donations from the rich who don’t care who wins and just want to curry favor with whoever will be in power.

I’m not saying it has no effect but it’s hard to tease apart exactly how much.