I stop them early and explain I don't want to give them money, but thanks. (I'm on the no-call list and only get called by charities.)

When they try to explain how "even a small amount will...," I say "no". Then I repeat "no" and NOTHING ELSE (I don't need a reason) until I get tired of it and then say, "I'm gonna hang up now - bye" and hang up.

When I get off the phone, I'm not upset at all. The telescrounger's probably not upset, and I don't hate the people who are hired by charities to solicit money, so that's fine.