Not just the hobby world Chas.
I had a neighbour / customer who called me out at 4am because the WC cistern in his en-suite had cracked and he had water leaking through the ceiling.
He was well educated, a business owner with a number of shops and P.O. wealthy and of course didn't possess the commonsense to turn off the iso valve.

I isolated the cistern and emptied it and went back to bed, didn't charge him and spent a couple of hours sourcing a replacement which as it was a discontinued colour wasn't easy. Eventually found a bespoke maker in Durham but production was a month however they needed the cistern lid to colour match and so I told him he'd have to take that through to them before we could order.
His reply that I had to do that because it was my job didn't go down well and I can be a little blunt at times but politely said that if he wanted me to do that I'd have to charge him half a day labour plus fuel cost for the 80 mile round trip and he just lost it. It ended up with me telling him to go away and find some other mug and to never darken my door again then put a bill through his door for the call out which of course he never paid.
He came back a few years later asking me to do some work which I turned down though we were on speaking terms by that time.