The men that developed WhatsApp (Jan Koum and Brian Acton) worked in Yahoo, later left, and went to Twitter for job, they rejected them. They later developed WhatsApp and sold it for $19 billion.

In 1997, after Google was set up, the founders (Larry Page and Sergey Brin) approached the C.E.O of Yahoo to buy Google for $1 million, because they were not making profit. Yahoo Inc. refused to buy, stating that it is a bad investment to buy Google for $1 million.

Six years later in 2002, Yahoo tried to purchase Google for $3 billion, but Google founders refused to sell, because they were already making progress.

In 2014, (six years ago), Google was worth $395 billion, while Yahoo was worth $39 billion - roughly 10% of Google's worth. Can you imagine what could have happened if Yahoo had bought Google for $1 million in 1997? Or if they had bought it for $3 billion in 2002?