Let us not ignore the fact that Congress also uses taxpayer money to buy votes and that only about 44% of households pay federal income tax, with the top few percent paying the bulk.
The more I see how the democratic platform has devolved in the last 4 years, the more I have come to understand and agree with the decision in Citizens United. Right now, we have at least two candidates talking about a pretty extreme wealth tax (which is a tax on money you've already paid a ton of taxes on) all because others are envious of what they have and just want to use mob rule to steal.
Allowing money to influence votes, in a way is not unlike how a bicameral congress works. We have one that has equal representation (the Senate) and one that has proportional representation (the House). Similarly, every one has one vote (equal representation) and the ability to donate money to influence those votes and the amount of influence you are able to exert is proportional to the amount of value you've accrued from mutually beneficial voluntary transactions with others in that society whereby you provided to them some good or service they found valuable (proportional representation).
Money in politics is one of the greatest forces for the protection of private property. Without it, we'd likely devolve into a place like Venezuela where private property is seized unilaterally without recompense because the people voted for someone who promised them that they would use the government's right to licit first use of force to take private property from private citizens.
Had Martin Niemöller been born in pre-Soviet Union Russia or pro-Chavez Venezuela, he might have started his poem this way instead:
"First they came for the billionaires..."
Eventually, they'll come for the middle and upper middle class like they've done in many countries that become communist/socialist in the 20th and 21st centuries.
This is not to say that money in politics isn't a corrupting force, it is. But a democracy is also corrupting. The two balance each other out.
"A democracy cannot exist as a permanent form of government. It can only exist until the majority discovers it can vote itself largess out of the public treasury. After that, the majority always votes for the candidate promising the most benefits with the result the democracy collapses because of the loose fiscal policy ensuing, always to be followed by a dictatorship, then a monarchy." — Alexander Fraser Tytler (possibly Alexis de Toqueville)