It would only affect the top 1%? Horse manure!
Imagine that you are a top 1% wage earner. You have a choice with what to do with your extra money. You can either take it and give it to charity, and not get a full tax deduction, or you can take it and invest it in your business, and get a full tax deduction, or you can keep it, and get taxed on it. So whatcha gonna do? Maximize your tax benefit, right? So charitable giving goes down. And the other 99% of Americans feel the effect, when CHOA can't get the new piece of medical equipment, or the Ronald McDonald House doesn't build a new wing, or Habitat has to cut back on its plans, or the Red Cross doesn't have enough blankets in an emergency.
So the needs don't get met, right? More horse manure. We can't let people not get emergency care, or housing, or medical care. Government steps in to help, with dollars borrowed from our children and grandchildren. We'll just raise taxes a little more on the top 1%; they can afford it, because they aren't giving as much to charity as they used to.
Meanwhile, back at the ranch, we've got a huge surplus of horse manure.