Kathy Weston describes in Science Careers how she came to leave her position as a research scientist in Britain: "Falling Off the Ladder: How Not to Succeed in Academia". It's a powerful dose of self-reflection, and has lessons for young scientists looking to move up the career ladder.
What could I have done to check my descent into mediocrity? I should have put aside my fears of looking dumb and got on with the networking stuff anyway. And -- very importantly -- I should have found myself a mentor. Every scientist needs someone in a position of power who has faith in his or her abilities, to provide advice and do a bit of trumpet-blowing on his or her behalf. I should have taken more scientific risks, gone for bigger stakes, and thought harder about direction. Finally, I should have followed my instincts and quit my job before it quit me -- but I was hampered by an exaggerated terror of being labeled a failure.
From tenure, she found herself increasingly dissatisfied, partly because her priorities changed, partly because of the treadmill of maintaining a lab. I hope she will write a longer version, I'm sure there are interesting tales.