If you start analyzing unicorns, you notice that most of them were not pursuing blue ocean strategy. They were entering red oceans of competition doing something differently and then winning their fight.
Why is this so? I think if you are going after big money, you should target big and therefore existing markets. If you can win over a competitor, you can win big. If you can win over a traditional way of doing something, your win can be even more prominent.
On large existing markets, the rivals are driving the margins down to zero, so you should be different. But I still think its easier to fight the competition, rather than to create demand for the non-existing market. So bye-bye blue ocean.