Have you ever had a client not pay you for your art?

I have not had an issue where I have not been paid for art or graphics I have created for someone but when I was heavily in the video game content creation world, I noticed a lot of artists who are hired for graphics such as emotes or even logos used to go without being paid for their work and that was always a shame to see as their work was always amazing.
 
I trusted a family member once who kept promising me I'd get paid. I had designed something for a company he worked for and I asked for 6 months for payment and all I heard was promises. Since then, I learned that contracts are necessary, even for family and friends.