I'm going to be in the process of drawing all my characters in exchange for ones I have pictures for from the internet. If someone specifically doesn't want me to use their picture I'd take it down for sure, but don't personally see it as a big deal if they don't mind, even if I do admit it can be a little lazy if they have the talent but just want to take a random picture from somewhere. I'm not upset at all if someone uses my drawings as long as they don't claim it as their own or make money off of it/stop me from making money off of it if I become desperate and turn to drawing for money. I can take pride in my artwork and enjoy if people are having fun with it/looking at it.

There's nothing wrong with people who want to keep it to themselves, just not my cup of tea.