leaving academia

There's no easy or fast solution for feeling good about leaving academia, because you're giving up some aspect of your identity, and even if you can convince yourself that it's 'good riddance' it still takes time to rebuild a new positive identity around other things. It's kind of like breaking up with an extremely long-term partner: even if it's true that things weren't working and the breakup is best for everyone involved, there's no way around the fact that it's going to suck for a while until you find something or someone new to get into.

Some thoughts that have helped me feel better about not being an academic.

• As a student I often felt stupid because I saw academics working on some topic and I thought, "I never would have thought of that; they must be so smart to have identified this as an important topic to work on!" But with time I've come to see that in many cases the topic was not in fact important. I'd been assuming that I should care about it because other people cared about it, but in a lot of cases that was just wrong.
• Working in an industry research lab has been great for coming to see how unimportant most academic work is. Academics will publish a paper saying, "we show how to do X" where X is something that sounds really cool. But in fact, they've shown how to do X in a toy context that doesn't account for all the complexity a real-world system has to face, and in a way that relies on different concepts/techniques/representations than what's currently used to address all those real-world complexities. They congratulate themselves on having 'solved the core problem' when in fact they've just done the easy part, and in a useless way.
• Being paid an industry salary may feel like 'selling out', but you can also see it as a market signal that society actually values what you're doing. Sure, some academic research creates a ton of societal value that it doesn't capture, but a lot of academic research is genuinely useless, and average salaries in academia reflect this.
• I have some really smart friends that have been quite successful in academia. It was really hard to see them get top jobs and to see myself as a failure by comparison (even harder to hear them complain about aspects of these jobs and feel totally unable to sympathize). But stepping back from the academic status hierarchy, I can ask myself the questions that really matter to me: who's ultimately happier, who's having a larger impact on the world, who has more freedom to pursue the things they're interested in? A few years later, it's no longer clear to me in a lot of cases that the academics are winning on these metrics. The combination of having made some money and not being locked into the academic career ladder means that I have, in practice, a lot more freedom to find work that I really enjoy doing. (at least this is the optimistic take). And for the aspects of work that I don't enjoy, there's no expectation that I'm doing them on nights or weekends.
• I don't think this is everyone's experience, but in my mind there's an analogy to the mental shift of coming to terms with being gay. I felt like a failure in high school because I didn't have a girlfriend; I was doing badly measured by the social status hierarchy that I'd been conditioned to value. Eventually I came to realize that my 'failure' wasn't a lack of ability so much as a lack of motivation: I'd failed to achieve the thing that society expected of me because there was an aspect of it that never felt quite 'right' to me (namely that my partner should be a girl). It was hard to see that as a failure on society's part rather than of me, but once I did, it was tremendously freeing (in the immediate sense of hot gay sex, but also the broader sense of realizing that, if all of society's institutions could be wrong about this for thousands of years, they were probably wrong about a lot of other things too). You can take the analogy too far, but there is a sense in which getting an academic job is the 'straight' path that smart kids are conditioned to follow, just like having a wife and kids, but there's a whole world of other possibilities. In both cases, it's a lot harder to have to figure out a different path 'from scratch' than to follow the societal template, but it can ultimately be more rewarding.
• Teaching is the thing I miss most about academia; in industry you can have internships, etc., but it's not the same. Still, I think it's pretty easy to get hired as an adjunct lecturer to teach an occasional university class if and when you want to (and am hoping to test this at some point). Most 'real' professors are desperate to get out of their teaching responsibilities---even if they enjoy it in principle, it's stressful to have to balance the time against research expectations---so if you're a qualified person willing to step in, care about doing a good job, and are able to self-fund taking time off from other work (so not super motivated by money), that's potentially a win-win-win for you, the university, and the students.
• Seeing friends (all of whom have various flaws) go into academia has been useful for coming to realize that academics are flawed people. Like I used to idolize professors as smart people who understood the world better than anyone else, but now I actually know a lot of professors and they continue to be just as narrow-minded and wrong about things other than their core research topics (and sometimes those too) as they were before becoming professors.
• For me it also helps to read takes from people who were extremely successful in academia and yet still chose to leave. E.g., Matt Welsh was a Harvard CS prof who quit a while ago to work at Google: http://matt-welsh.blogspot.com/2010/11/why-im-leaving-harvard.html