Lots of people are announcing they're doing this now. If it was a genuine choice based on an inability to cover the cost of both, then fine. But most of the people I know who are doing it can more than afford to send some cards and give some money to charity. Also, why say the thing you're not doing is the thing that brings pleasure to others? Why not say, I'm going to have one less bottle of Prosecco this Christmas, or skip the fancy chocs or whatever, and give that money to charity? Just be honest and say I can't bothered to send some seasons greetings to the people I like. I think it's mean.