I don't understand this continuous debate as if there is some sort of "loyalty" required of your customers. I know of no other industry that store owners feel betrayed if their customers went somewhere else to buy. Sure, they may feel disappointed, and that's good. But that disappointment should be introspective, wondering what they could have done to keep a customer.
If I remember right, there was a time when catalog sales were hailed as potentially harming the LDS.
For the last few years it has been the online sales.
Remember, they are just dive equipment sales just like anyone else. I've seen LDS grow in spite of this competition, and I've seen some go away. If you don't keep your business model effective, you're going to go away. I've seen too many dive shops run like a hobby rather than a real business.
If you can't compete using your current business model, you've gotta change. If you don't think change is necessary, just ask a dinasaur how that worked for them.
Look, in a competitive market, an LDS CAN compete. If you offer competitive prices you can win out over other competition with service. If you can't offer competitive prices, then you need to figure out how to do so. Those on line sales places have brick and mortar backing them up too, they're not operating out of the back of a van (I'm pretty sure, at least), so they have the same bills to pay as the LDS but they've just found a better business model.
There will always be those who will prefer to look, touch, and try locally rather than buy off of a web site. The opposite is true too. Some shops will make it, others won't. A love to teach scuba and a love to be in the industry doesn't mean that your business will make it. A simple, yet harsh reality of open-market economic models.