Some people think they control everything about their lives -- they do think that if they put in the time, effort, and energy, they can achieve anything. When they don't, they blame themselves endlessly. Sometimes, learning that it was something beyond your control (ie social forces were stacked against your particular endeavor) can be liberating and break the person out of personal blame an hopelessness and let them start again.
On the other end of the spectrum is feeling like an endless victim. Sometimes, it's easy to blame everything and lament how everything is stacked against you. This provides psychological solace but can prevent you from moving forward because you're convinced you won't be able to. In these cases, some of the stories of 'self-made' optimism can help get you out of a spot of hopelessness into action.
In this situation, though, what's medicine to one is poison to the other. I can think of times in my life where each view was helpful and warranted, even if they're hard to reconcile with each other.
In this case, the 'truth' isn't really knowable because we can't objectively observe a system we're a part of. So, until we know, I guess it's whatever view gets you where you need to go.