Maybe he didn't leave his mark as a programmer/engineer the way HE wanted to, but you definitely have to admire his ability to identify good opportunities. He laments choosing and then using LISP for so long and in a way seems to blame the language for adversely affecting his perspective on programming, but it really seems like it served him well when it was useful. I think the same intuition that helped him choose LISP for solving problems (because it was a nice set of tools at the time) probably ended up helping him choose good professional opportunities, too. If he's frustrated about the way his perspective changed then I have to agree with the other commenters that he would need to work on changing that perspective and not remain complacent.