Seriously?
Because the representatives who voted to cut benefits and services wouldn't be re-elected. No mystery.
I am good with sending them as little as I can get away with.
Good for you. As long as you don't want a military, Medicare and Social Security and can convince your fellow citizens to give those things up too, I applaud you.
Otherwise, you're whistling past the graveyard.
Like I said, There is absolutely nothing stopping you from sending as much as you want. Here is a link to help you with that.
https://www.fiscal.treasury.gov/fsfaq/faq_gifts_to_govt.htm