Here's an interesting article on DIY Filmmaking from IndieWire.
Part of the reason people pick up a paint brush and put it to canvas is because they can't find a compelling reason not to. In that same vein, picking up a camera and making a film follows those same principles. "What kind of story do I have that's interesting to tell?" "What crazy idea that I was thinking about the other day would make an interesting short film?" "I've always wanted to show this story, to tell my story, and I think it would make a great film."
We've all thought the same thoughts, but today people can actually put what's in their head onto canvas, or onto another medium. And further they can craft it into a story with a beginning, middle and an end, with a few twists thrown in along the way. The same rules of story telling apply to documentaries, or any story that is begging to be told. What's the ending? What's the event that turned our main character into something else? Once I've set up the premise of this story, how can I further explore that premise through focusing on that sentiment or reality? And who "saves the cat?"
It's just a matter of turning the dang camera on. Or in the case of a film at Sundance this past year, turning on their iphone 6.
There's no reason you can't tell your story. Get to work! (And then send it out into the planet so we can all share in that vision, and honor it with accolades)