I think that the big take-away from this shouldn't be: "don't build an application in X market" it should be "build a niche application in X market". There's n

I think that the big take-away from this shouldn't be: "don't build an application in X market" it should be "build a niche application in X market". There's no way that you can compete easily with Facebook. But maybe there is an opportunity to build a social network for people that specifically don't want to share their real identities. Maybe you can't compete with Word, but how about a word processor specifically designed for vision impaired users? The internet is a huge marketplace. If you choose a good niche and cater to it then you'll more than likely find a enthusiastic audience.