Many people in the valley would say "Startup is for opportunists". This one explains why. Please read this one with a grain of salt since I think the scope for this one is mainly for technology startups that are built to take advantage of a new enabling technology. But still, it's good to see the point from the other side.
In technology, long term thinking is impossible, because everything changes so fast, and the pace of change is quickening. The rules are changing too fast. Nobody knows when a sudden shift in technology will open up new markets and business models.
All we can do as entrepreneurs is take it step by step, and adapt quickly when we sense the market shifting.
To set the scope a bit, I do think the team, the industry and the understanding of the target market shouldn't change over time. The knowledge of why people pay for the service should stay the same. The connections wouldn't change that much.