The academics I work with, for instance, prefer Python, tolerate Java, do OK with JavaScript, but run for the hills when they see Lisp. When I tell them that ClojureScript not only has semantics with consistency that will elicit sobs of joy, but is also historically the most stable and concise way of targeting JS in the browser, maybe a few of them will be interested, but as soon as I show them a code snippet it's all over. They turn their heads sideways, they frown so that their lips are like the parentheses that splay before them, they mutter something about parentheses, and they go back to tripping over themselves in JavaScript trying to remember which Array functions are mutating or pure.
Learning a new syntax makes you feel dumb, even if you know how to program. And if you're feeling dumb while you're working on something that isn't even strictly related to the problem you're supposed to be solving before your deadline, it starts to get really hard to justify it. Most people only know something with a Python-like syntax, so most people will only ever work with languages which look like Python or Java since it's what they learned in their programming curriculum. It's ALGOL's world, and Lisp's just living in it.
Who does learn Lisp, then? I'd say, from what I've learned about the people in the Lisp world: mathematicians and computer scientists with intrinsic interest in PL's or the mathematical underpinnings of Lisp, old school symbolic AI researchers, and grizzled software engineering veterans who believe Lisp-family languages are engineering weapons of choice. All of these people have motivations (interest in mathematics and PL's per se, an academic interest with an historical connection to Lisp, and an insatiable itch for an ever more comfortable hammock even if it means getting out of the one you're in right now) that do not apply to the larger class of programmers that I just described.
I wish it weren't so. I wish more people would take the time to learn Lisp or an editor like Vim or EMACS: we, ahem, enlightened ones, know what a pittance the upfront investment will come to seem when the benefits of a superior tool are reaped over a lifetime, but people do not listen or do not believe when we tell them so. (Maybe they're right.) Perhaps we should ask ourselves what could make the promise of our salvation more credible.