It is absolutely not useless. But good business sense. My images are my
business. And I value my images.

Hmmm, I get a lot of people looking at my images on my websites. Hmmm, I get
a lot of people to buy and license my images from my watermarked images. So
that just shot down that theory.

To say watermarking will not "deter anyone" is just plain wrong. Most web
surfing people (who like to steal images off the internet and use them as
their own) don't have the expertise or the pro applications to Photoshop the
Watermark out of a image, let alone do a decent job of it. So right there
you have stopped many potential thieves.

Sure there are always some Photoshop knowledgeable thieves that might try
and "Clone Stamp" the watermark out. But even the Photoshop aware thieves
will have a problem getting a quality image even if they do spend a fair
amount of time on it. Plus, that is another reason not to put large size
images up online. That also makes it easier for the thieves to Photoshop the
watermark out.

I do photography for a living! Do you?

Funny, the cropping and cloning I've found done to some of my
photos didn't stop the watermark from being detected.