Really good ideas can be started at any time, and don't suffer from competitive pressure. The way i see it, there are two categories of products: gold rushes and fishing expeditions. The social space is a classic gold rush scenario. The winners in that space won almost by accident, and someone else could have easily taken their place. Google on the other hand started as a fishing expedition. If they hadn't built it back when they did, we might have used altavisa for another 5 years and been none the wiser.