And the IRS allows you to contribute as much as you prefer to the treasury. It's voluntary and no one is compelling you.
So that group of billionaires who think the government can use their money more efficiently than they can in order to advance American society are absolutely free to do so! Go them! They don't need the government to compel them. They can form their own Philgubernatorial group -set their own donation rules and taxation (donation) bands and percentages and come tax season give it to the feds.
