Ask HN: Solving a problem vs grabbing an opportunity?

Solving a problem you have often leads to great startups if the market is big enough, examples are Dropbox and Airbnb. But if I am seeing an opportunity in a specific market which has the possibility of becoming a huge success even though it isn't a problem in the traditional sense and wouldn't make a ton of difference if it didn't exist (probably someone will do it soon, anyway), should I pursue it? Have you pursued such opportunities yourself and have become successful? Or do you know of any examples of big successful companies who have started that way?

Assume : 1. I have enough domain knowledge, insights and expertise to grab the opportunity well. 2. The definition of success here being a market leader or having a significant market share in that category.