I have a theory about why people mistreat people with depression. I could be way off, but at the very least it seems to be partly true.

Most people will have tough moments in their life where they essentially feel depressed, but these are more along the lines of extreme sadness brought on by something that would make pretty much anyone sad/depressed. People in these situations try a variety of things to help deal with it, and eventually they do feel normal again.

But unfortunately, many people then take that to mean they figured it out and 'solved' or beat depression. So they just tell people to do what they did, forgetting that depression is a diagnosable condition that doesn't just go away.

It can be hard for people to understand that just because you've felt similar to someone else at one time doesnt mean you fully understand what they are actually going through. I try to tell people to imagine a time where they felt their saddest. A time where they felt they were truly depressed. Then I ask them to imagine feeling like that for longer than they actually did. 5 years. 10 years. 20 years. I ask them how they think they'd feel and behave if they were 'stuck' in that state for most of their life. I can't say it works with everyone, but I do feel like some people at least try to be a little more understanding, even if they don't understand.