somebody needs to pay for the billboard, or rent a hall to give a speech, or printing the flyers for your lost cat. How is money not essential to speech? Your proposal is that to support a cause, one should only be allowed to go outside and yell, because that's purer than the corrupting influence of money?
Once money gets involved, you inherently have a commercial interest. What's the ROI?
I personally think people misunderstand to whom "freedom" is granted and defended in the US, it is demonstrably not freedom of the individual, but of the powerful.
free speech is a legal concept, and ROI is not a legal concept; when debts are enforced by courts, they frequently don't even enforce interest as if time value of money doesn't exist.
The nature of the strawman you've stood up to to represent my "proposal" (who knew I had a proposal?) suggests you're not even familiar with the history of the legal debate in the United States surrounding the 1st amendment and political donations. So I guess I would propose you read up on that.
