A lot of very effective democracies work better by making it so that one individual is does not have a disproportionately larger voice, so the idea that you can spend arbitrary amounts on speech just because it's speech doesn't really follow.
Doesn't the FEC already regulate contribution limits? The debate is where the line is and when the line comes into play. Society is a constant negotiation between individual freedoms and collective safety/social order. You have already ceded some rights in this vein. It is not controversial to see an unfairness in some citizens/their vehicles having many magnitudes more influence over the common citizen. Citizens United is a conduit to a standard that can be hacked by money. Arguably, the dilution of your own political leverage in this paradigm is a greater inhibition to your rights than a stricter contribution limit ever could be, in the long term.
Except in your world the person with the most resources is the one that wins by default because they simply outspend everyone else, how is that righteous? Especially when we're not talking about individuals here, we're talking about corporations.
Besides your premise is flawed to begin with, you most certainly cannot freely rent out a billboard and put anything you want on there, or a radio ad, or a book printing. Restrictions on content already exist, and I see no reason why an exception should be made for political parties.
> the person with the most resources is the one that wins by default because they simply outspend everyone else
As the heir apparent of the republican party, Jeb Bush raised a half-billion dollars from donors. He was politically connected, with a history of winning elections. His significantly outspent the other candidates -- and still lost. This isn't especially uncommon, money's influence alone doesn't determine elections.
How many people who weren't "heir apparents" of extremely wealthy families/parties ended up on the ballots, though? Basically every US election comes down to a choice between 2 uber-wealthy people, and sometimes a 3rd equally uber-wealthy one manages to break through with some votes.
There isn't a chance in hell with the current system that anyone who doesn't come from a wealthy background, or at the very least has the backing of a rich sponsor, would make it anywhere near the top of the list, which is the entire issue.
That doesn't mean money doesn't tip elections, it just means sometimes money isn't enough. Anyone who has played a pay to win game could have told you that for free.
You shouldn't have the right to spend disproportionately more on influencing an election than other people. That's not democratic. It very much favors the interests of the extremely wealthy.
What would be most democratic is if tax money funded campaigns. Every candidate gets the same amount for that office. Take money out of the equation. It should not be a reason someone gets elected. That's corrupting and makes candidates beholden to monied interests.
> You shouldn't have the right to spend disproportionately more on influencing an election than other people
The 1st amendment freedom of the press is by nature disproportionate!
Most citizens do not own a printing press. Most presses aren't upstream of a national distribution network. Not all twitter accounts have millions of followers. "Evenness of influence" is not constitutionally guaranteed or even a natural outcome, even in a democracy.
The 1st amendment doesn't guarantee you access to the most power communications equipment and audience, only that that the Government won't suppress what you manage to obtain.
Don't I have a right to buy a $10 yard sign? A $100 bard sign? A $1000 billboard? A $10K radio ad? A $50K book printing?
Why should I lose any of these rights because I join with others to help me afford it?