1. The Citizens United ruling allows unbounded money to flow into campaigns.
2. Campaign funding determines election results.
3. Elected officials determine what America does in terms of law and regulation.
4. Billionaires pour tons of money into campaigns.
When you allow dollars to effectively determine elections instead of votes, the end result is oligarchy and the rule of the rich.
https://www.washingtonpost.com/graphics/politics/2016-electi...
Also, it's a completely different ball game talking about which laws get passed vs which candidate gets elected.
Is your claim that above a certain dollar threshold money no longer has an impact?
A relatively smaller amount of money will influence state elections, and state-level politicians determine things like district boundaries (i.e. gerrymandering), vote roll purges, polling stations, etc. All of those have a very large impact on elections too.
2. Trump still raised about a billion dollars. That is an insanely large amount of money.
3. Campaign financing for elections and financing for lobbying for policy are different things. For the latter, it is all but proven that financing is all that matters: https://www.cambridge.org/core/journals/perspectives-on-poli...