Leaving academia after graduate school

This page considers questions such as:

If you're nearing the end of a Ph.D. program, and expect to finish it in the near future, what factors should you consider in deciding whether to continue in academia or leave it?
If you're in the early stages of a Ph.D. program, or have completed a Masters and want to continue to the Ph.D., and you are not interested in continuing in academia, should you finish the program, or quit immediately without a Ph.D.?

Books with advice

Grad Skool Rulz, online articles plus an ebook based on those by Fabio Rojas, professor of sociology at Indiana University.
A Guide to Academia: Getting into and Surviving Grad School, Postdocs and a Research Job by Prosanta Chakrabarty

Get a PhD—but leave academia as soon as you graduate by Allison Schrager, February 7, 2014, Quartz, advises people interested in academia to complete their Ph.D. but quit academia after that unless they can find a good post-doctoral position and have strong interest in continuing in academia. She argues that the low retention rate in academia and the "pyramid scheme" need not be viewed as a problem with academia, as long as people starting on graduate studies are explicitly aware that they are unlikely to continue beyond that.
Some of the answers to the Quora question Why did you leave academia? explicitly discuss people's decisions to leave academia after completion of the Ph.D.: Vipul Naik's answer
Why I Left Academic Mathematics by Brian Mann, February 13, 2014, on his personal blog describes his decision to leave academia after obtaining a mathematics Ph.D.