[Kate*]

It's obvious based on your post that you don't understand and as someone who has suffered from this illness, and yes it's an illness for half of my life I'm torn between understanding that you just don't get it and being offended. It is often caused by a chemical imbalance and can affect ANYONE at any time in their life. It doesn't have to be triggered by anything, it can just happen and a lot of the time the person who has it knows that they have nothing to be upset about and wants to be happy yet they can't help feeling completely miserable for no reason. We aren't crying over what we do or don't have or because we think we're entitled or because we're selfish, it happens to us because of a physical problem with our brain. If you'd like to understand it then I'd be happy to explain it to you, but if your goal in asking "what the deal is" is just to rant or try to snap those who suffer out of it when you can't understand because you haven't lived it then that's something else.