I know of three friends that are using Windows XP.

According to them, it works, and does what they want it to do, which is to write a few letters and to browse a few websites. They are hardly power users. They have tablet computers which, for them, is good enough for most of their frequent web browsing. They all have the same outlook on it and when it packs up they'll decided what to do.

As has already been said - if it works, why change?

I have among the machines where I do voluntary work one with XP, it is primarily used to maintain membership records on a M$ spreadsheet - it doesn't connect to any network at all. Some mischievous souls say there are games on the machine when owing to extreme weather we aren't likely to launch a rescue, and radio operators may become bored on their watches.

Many Grannies do that as well [play solitaire] in between sending emails without subject lines...

In our case - why would we waste precious donation/fund raising money on any update?

Absolutely right. I spoke with a charity last year and they said they would be happy to receive a donation to upgrade, however, as the charity mentioned, if somebody donated some funds, they'd probably spend that on the good cause, because the computer didn't need updating.

The only problem I foresee is if someone accidentally introduced a virus. XP would be more vulnerable than a later OS. However, as they said, when they did need some support in the past they didn't get much help from Microsoft, so even if they went to Win 10 they don't believe that would change. They'd still be on their own.

The hardware/software update cycle is well and truly broken.