Your teachers and friends are wrong. It is that simple. I have the job I have now because I am a mid-level Perl programmer. Check out Perl Jobs, there is plenty of work for good Perl programmers.

I have programmed in other languages, PHP, VB, VBScript, C#, but I like Perl. I am a better programmer in Perl than in any of the other languages because I like it. And yeah, I could probably make more money if I was a Java programmer, but I would not like it, and would probably not be very good at it.

Bottom line is;

• You can make money by being a good at Perl because there is a demand.
• If you like it, you will be good at it (with work/practice, of course)

A few other points to consider:

• It is unlikely that you will program exclusively in Perl anyway.
• A lot of what you learn in Perl is what you learn in other languages anyway, so learning in something you like will simply enhance/speed up your learning process in other languages
• Perl is a tool, not THE tool. Other tools (C/Java/etc..) will be better applied in many situations. ( I like to prototype in perl, then migrate to whatever else is better suited)

Hope this offers something meaningful. :-)