Most people dont take mental health seriously because it's not something they can simplify.
When you get sick from cancer, strep throat, the flu or something you know it's time to get help because the body shows it.
You get an injury outside the body you can see it so you know to get help.
People really underestimate the power of the mind though because humans like to simplify things. You can't really see the mind getting sick so the best explanation is that it's not that bad, but that just proves how powerful the mind is. If the mind can see pain it understands it needs to do something about it, but if it can't then it convinces itself that it's not that bad.
People need to learn to treat their minds better because it can get sick like the rest of you.