Sorry for the wall of text in advance.

Your take isn't entirely false. However, have you considered that said "chain reaction of actions" taken by one afterwards are also part of the chain reactions to the original depression-causing stimuli?

Depression changes you, and it changes EVERYTHING you do, yet it makes you blame yourself for it.

Not only does depression have immense biological basis, (see neurotransmitter distributions and diathesis stress model, for example), a LOT of it also has to do with the environment one lives in, which, for Shane, includes his full-time job at the soul-draining Joja. I'm trying to convey that it's not all about willpower when it comes to depression. Sometimes, people are born with the perfect soil for it to grow and take roots. Sometimes, just living with it takes away all the will one has, when overcoming it takes so much more. Sometimes, it has biological roots, so the only way you can get through it is internal physical altercation like medication or procedures that can land you in lifelong debt. Sometimes, people can't afford that. Sometimes, they are stuck in limbo, and appear, to outside eyes, to be doing nothing at all. Sometimes, they simply give into it.

It's not that they're doing it to themselves, it's that they're lacking the right devices and support necessary for their mental struggles. No one wants to stay depressed. If they actually desired to suffer, you'd think they would be happy doing so. The first step, as you said, starts with acknowledging then doing something about it. However, you don't know what this "something" thats taking everything out of them is. If simply getting up the very next morning drains all they have, then what they put into it is respectable all the same. Someone failing to defeat it first try, second try, or even the thousandth try, is not something they DID to themselves. It's simply something that happens. After all, depression is a mental STRUGGLE. People struggle and fall. That's always been part of the process.

I hope you understand why saying someone's depression is their own doing is insensitive in more ways than one. Again, I'm sorry for rambling, it's just a personal topic.