Not to sponsor someone's holiday?

Grandmanorm my friend did the Great Wall walk too and also two others. Each time she paid all her own expenses and had to agree to raise a certain amount of money for the charity before she was accepted to do the challenges. She did not ask for sponsorship but organised a number of fun events and close friends did help with these events and donate time and maybe cakes etc. All these were good social events attended by lots of people. She did a couple of things which would not have been so easy to do alone and paid every penny of her costs besides raising several thousand pounds for cancer charities. Things are not always so clear cut as we assume.

Admiration grandmanorm!
I've just 'sponsored' a friend who walked the Camino. He paid for all his expenses, obviously, and enjoyed his little 'holiday' but also raised a fair sum for Alzheimers Research while doing so..
When she was 17 DD3 went to India and worked in a school, building classrooms etc. She raised every penny for the trip herself - worked in the local golf club, made 'stuff' and sold it at fairs and at school and also used her birthday/pocket money to fund the trip. It certainly introduced her to the value of money and made her aware of the plight of others.
A friend was recently asked, instead of giving a wedding present, to donate to the happy couple's honeymoon in Bali. She contacted them and said it was against her principals and would they like some more bath towels instead