Hey, even if you accept their premise that monetary contributions, etc don’t qualify as “speech”, the government still doesn’t have any authority to put limits on who we can give our money to for what and how much. That’s one of those unenumerated rights reserved to the people and the states.
If government can regulate political donations, then there is no practical limit to what economic activity the government can regulate, is there? We’re not talking about wages or prices or something where the government can posit a need to step in and arbitrate between two opposing groups of citizens. This is a gift that is freely given and freely accepted that the government wants the power to interfere with. There’s really no justification, except that the government WANTS to regulate it.