Yeah, I've come across that before as well. Or people who volunteer you to do something because it makes THEM look good, and then get upset when you refuse to do it for free.
My spouse's hobby is working with laptops/pc's/tablets. It isn't what he does for a living (or even close), but he loves to do hands on type stuff with technology. He is a perfectionist who takes the time to make sure everything is working correctly, so if he builds you a computer, it will work correctly right from the start.
He has had to tell people that if they ever volunteer him to work on a friend of a friends computer, or even another friend's computer, he will no longer work on their computers. He only charges for the parts, which makes him very popular as a computer hobbyist/builder/fixer.
I actually ended a friendship in part because that particular woman just loved to volunteer my spouse to fix all of her friends and families computers. My spouse had only kept her computers running because she was my friend. And a difficult job it was, as she was one of those persons who never met a link that she wouldn't click on or an email she wouldn't open, along with the attachment.
She became angry with me when my spouse told her no, he wouldn't fix her next door neighbors brothers computer. That, along with a bunch of other bad behavior, was a large part of what helped me to realize how one-sided the friendship had become.
My spouse said that he thought she loved being the hero, but didn't love having to actually do anything to deserve the accolades. Volunteering my spouse made people think well of her and she craved that attention like a mosquito craves blood.
My spouse is so firm on this rule of not being voluntold to work on other people's computers that he has one brother who he will always take the time to help and one who has to pay someone else to fix his computers after multiple incidents of volunteering him to work on people he had never met computers.