Why do people not believe us?

A lot of us are neet because of our mental disorders but I always see people laughing at that. Like it’s just a stupid excuse for lazy people. My own dad is embarrassed by the fact that I’m so dependent and calls me lazy all the time. I get it can be hard to understand if you don’t experience it yourself but even other people will say “I have anxiety and depression but you don’t see me sitting on my ass doing nothing all day!”. It just makes me sad that I’m suffering so much and my own family doesn’t even believe me.