Do you think it's right to contribute to a charity walk that's happening abroad?

no, I don't agree with these organised things. The participants have to raise a couple of thousand to pay for the trip and the rest if any, goes to charity. The only benefit is to the organisers. I would probably include the London Marathon in this. We have our own charities, they do not involve walking the wall, nor climbing Kilimanjaro, they are just simply giving to those who need. The donor (me) can then slump in their armchair and watch telly