Money has inherently corrupted a large portion of American politics. It isn't even trying to hide itself. Multiple politicians, presidential candidates, sitting members of the house/senate have received millions or even more from varying organizations. This isn't simply a gesture of goodwill, millions of dollars aren't a simple gesture but a move to make the politician be in debt to your agenda. Allowing millions of dollars to flow trough what is called "lobbying" at this point is corruption. This disrupts directly what the voters want. Imagine voting for a promising candidate only for them to change policy after you voted because some organization donated millions of dollars. That is not fair to the voter.

Voters do not get the final say. You cannot just cancel a vote after it has been cast. But a lobbying organization can withold to give funds any moment it wants. Campaigning costs, which is a big fault in the American system. Campaigning itself shouldn't even exist in it's current form. Currently it only encourages politicians to take money from super PAC's and donors instead of a European system where you do not need a lot of money to campaign. Simply put a entity which has the capability to change a politicians agenda on command is a threath to democracy and the votes of the citizens.

Your argument inherently lacks much of anything truly factual. I do not have to imagine a voter who sees endless ads by donors because that's the reality we live in. Opponents can use money to drown the media with their own campaign taking attention off a opponent that has less funding. This is especially apparent with pro big tech or pro Israel politicians which get large sums of money from corporate PAC's or AIPAC which can and usually will be used to create this noise. It just isn't fair for the voter. Your vote should have utmost priority, but instead it has to compete with PAC influence.