Seattle was the entry point for much of the Klondike Gold Rush, and the signs of those boom times are still all around (Nordstrom's and Pioneer Square are products of the gold rush). The signs of the California gold rush in 1849 are also still alive and well, so I think this analogy will resonate with the folks down in San Francisco. The point is that despite the boom/bust nature of the gold rush, sustained wealth was created, legacies were left, and the economy expanded. Web 2.0 isn't a bubble that will leave everyone hurting, it's a gold rush that will leave a significant impact on the tech landscape even if some fortunes will be lost.
Just like the gold rush, Web 2.0 has more than its fair share of individuals trying to strike it rich. A majority of these individuals won't hit the bonanza, but a few will. However the real money being made will come from people catering to the "gold miners". During the gold rush, banks, shop keepers and other entrepreneurs saw a chance to both help the miners and make money off of them. That was where the real fortunes were made, and the same will be true for Web 2.0. Financial advisors, Venture Capital firms,"Mike Arringtons", and other people who both foster and make money off of the Web 2.0 industry will do quite well. This is due more to the entrepreneurial nature of these people rather than any exploitative drive, just like (most of) the gold rush entrepreneurs.
But when the boom cycle ends, as it surely will, the Web 2.0 innovators will have left a legacy of ideas and technology. Today gold found during the gold rush is still valuable, and the ideas that come from Web 2.0 will be equally valuable. The Web 2.0 boom will have done immense good for the economy as a whole. The infrastructure built to support Web 2.0 will foster new ideas and new growth avenues, just as the infrastructure built during the gold rush was the beginning of large metropolitan areas. Some people will have lost money, others will have made it, but both types will have left their mark on the technology landscape. Whenever the bust cycle comes for Web 2.0, we have made progress, and that progress will be built on. It will simply usher in the new age of technological innovation. Rich Internet Applications will be revolutionary regardless of whether we're in the boom or the bust. What matters is the technology - the gold of Web 2.0.