The world is littered with many "first movers" that have fallen by the wayside. Does anyone remember the Apple Newton? Palm blew them out of the water a few years later only to end up struggling as Blackberry's and iPhones took over the market.
I read Lucky or Smart
by Bo Peabody several years ago and the concept came up in conversation with one of our customers just the other day. Bo was one of the founders of Tripod.com, one of the original internet communities and a precursor to what we now know as Social Networks. His thesis was that success is a bit of both and I don't think he ever mentioned being the first into a market.
I thought of the book again today when I watched this video from FastCompany.com
There is no doubt that the good folks behind Facebook are smart, but they were not first to market and there were some serious incumbents already in place. Facebook got lucky and were in the right place at the right time with the right focus when their competitors stumbled and were able to ride it to the top of the social networking world. Their smarts helped them make their own luck.
In B2C eCommerce, there are very few opportunities to be the first in any market anymore. Don't sweat it. History has shown you can be second or third or tenth to market and still come out on top with smarts (good planning, focus, execution, & staff) and a little luck.