So if I am going to a wedding, where the bride and groom have asked me to take pictures, I should do what so that the pros are happy? Say no, just so that the hired photographer doesn't have any 'competition'? Excuse me while I chuckle. Any pro photographer that views me as competition needs to up their game, significantly.
I don't pretend to be a pro, so please don't go there, and I'm not eating into the profits of the hired gun - they still get paid. I am an amateur that happens to be decent with a camera, and I deliver something in addition to what the pros were hired to do - a print for the bride and groom, a gift from me to them to remember their beautiful day by. What is so wrong with that? I just don't see it. Perhaps you are stuck in your viewpoint a little bit too much here. There are other vantage points - that of the bride and groom, or whomever asked you to be there. What damage am I actually doing? What did the hired pro lose by me being there?
And believe you me I work in an industry where there are lots of hacks who pretend to be professionals. My line of work is in the HVAC industry, connected to all sorts of functions in industrial, commercial, and residential heating, ventilation, and airconditioning. A lot of people don't mind hiring people without proper accreditation to get the job done; friends, relatives, handymen that stretch beyond their capabilities - making mistakes in installations with things that can go boom, with burnt down homes or even apartment buildings as a result. What you talk about, with hacks doing the work of professionals, is everywhere; it isn't exactly confined to photography.