In school, I had a really boring stats class right after my OSes class and my buddy and I used to skip it and sit in the labs and code up CGI scripts. My school didn't teach Perl (or any other scripting language), but in our minds CGI==Perl, so we Googled and "learned Perl" from those sites that people now caution others about on the Monestary.
That summer, knowing Perl got me my first internship at a big company, where I was introduced the the Perl Bible. I read it practically cover-to-cover over the course of that job and that was really "learning Perl".
Sometime during the course of that job I discovered perlmonks and that was the first time I really started to understand the scope of Perl.
That new Perl knowledge led to a second internship, followed by a first real job, then a second. And along the way I never really stopped learning, with each job bringing new areas of the language to explore.
So really, skipping class (to learn Perl) has been the gift that keeps on giving.
In reply to Re: How many man-hours would you estimate you have invested in learning Perl?