1. Rob, I agree with you that a couple decades ago shamateurs tended to cut into work that the lower levels of professionals might do. I don't think they do any longer because most lower level professionals have disappeared.
2. But at the same time I have to say that if you can't compete and make a living in your chosen line of work, you're in the wrong line of work.
Please excuse the splitting of your paragraph as above - it's just to make the reply more clear.
1. I can't argue that point because I'm now out of it, but not because of amateur competition - few amateurs regularly produced bespoke calendar print runs of above thirty to forty thousand units.
The 'lower level pros' were not necessarily worse practitioners; mostly I'd suggest they were living in areas where the clients at the levels that produce (and can pay for) top work simply didn't exist. And for the Brits, not everyone has the fortune to be born in London or has the resources to move there; in my case, a very comfortable home in Glasgow wouldn't have bought more than a garage in fashionable (liveable) parts of London. It couldn't happen.
Weddings: I did some for a few of the first months I was out on my own, then I walked the Damascene church-steps walk, images of a smiling Bailey in my head, and said enough! fashion, which is why I own cameras, or back to the factory unit. I'm glad I got tough with myself - changed my life. Big wedding companies also hired shamateurs to shoot on Saturdays... the BJP often ran classified ads to that effect.
2. That's really a part of the problem I tried to address in (1) above: things that the local 'social photography' snapper could find to do, and often did very well, such as wedding, portraits and christenings etc. were take over in large part by the traditional uncle with a hobby.
Digital only made that bad situation worse, and I believe the subsequent conditioning of expectations, when the person who might originally have been a client, made his own snaps, and because of the intimacy with the subject could no longer see those images objectively at all, least of all make a call on quality. Hell, we face that challenge ourselves at all levels of expertise each time we make an edit.
In other words, I think my original idea in an earlier post about the industry having largely polarized is correct: the top of the pyramid is an ever sharper point, whereas the base is wider but less interesting or rewarding than it used to be, more crumbs than broken biscuits. For that to happen, I suppose we need the outline of the Eiffel Tower, always an elegant format.