I think this pro and amateur argument exists on every field in pretty much the same fashion.

Professional construction contractor vs handy-man vs DIYer
Seasoned IT professional vs college/high school kid who are into computers
Wedding photographer vs weekend wonders vs friend with a camera
Medical doctors vs patient who read up on internet postings/sites

I used to tell junior people at my work (IT) the difference between pro and amateur is that pros know what NOT to do - that knows the limitation of his/her own skills where as inexperienced goes boldly into unknown territory (and often do so unknowingly) and hurt themselves or client.

Now a days, everybody is claiming titles in unregulated fields. Expectation seems to be lower too. Kind of scary me thinks...