That's a very simplistic way of looking at things.
Pro photographers who are actually competent business people get things like exclusivity contracts and longterm deals. We also don't sell individual photos after the fact, we're contracted for the event for a decent amount and we give them everything. So if someone like you comes along and tries to move in, well, you can't. Even if your photos were better or cheaper, my clients are locked in. This makes watermarks entirely meaningless, since the people im interested in selling my photos to can't buy from anyone else anyways. There's certain situations where you need them (portrait proofs) but other than that I can't think of one.
Now weddings are almost entirely different, being the one-time events that they are, but ive found that people are willing to pay a decent amount for someone who is fairly well known - unfortunately im not, which sucks, since people have been doing this for 20 years, which remains the reason I do other things in probably 3-4 other areas. But ill get there. But you know, it brings up a different point, weddings are entirely unaffected since.. who shows up to shoot some random person's wedding?
To the point: there's business, and then theres getting drunk and attending an airshow.