I wish you would honestly answer this; did you leave cause academia was bullshit? That's why I left. I regularly talk to grad students all torn up about leaving academia, and I keep telling them that "industry" is just as worthwhile an endeavor as research. I feel like reading about your path you've come to the same conclusion.
Having read Matt's account of his actions, I agree with your reading. It feels like he came to believe academia was bullshit, but didn't want to hurt his close friends in academia. (Which is fine! You are using a throwaway account, no?)
Over time, I came to view CS academia as bullshit as well, but I am starting to reverse this view. Academia is inefficient, anachronistic, political, bureaucratic, and doesn't do a very good job measuring its own output. However, that seems to apply to countless other institutions, especially institutions with billions of dollars.
Is it possible that academia is a flawed system that sometimes has good results (e.g., new knowledge, startups, quality engineers) that would not have happened otherwise? Or have new inventions like incubators or online education arrived that make it easier to achieve those good results without the old, flawed system?