Are you under the impression that Citizens United allows for unlimited donations to political candidates?
It doesn’t. In fact, it specifically allows for limitations on contributions to candidates.
What it does say, quite properly is that government can not check a person’s ability to agitate either in favor of or against political candidates.
It struck down the asinine McCain-Feingold law which allowed the government to fine the Sierra Club for passing out leaflets criticizing the environmental records of politicians.
Everyone who cares about free speech should have cheered the decision as did the ACLU.
Obviously there are some paranoid people out there, but there’s no reason to allow our paranoia to make us use the Constitution as toilet paper.