Take google for example, from search to gmail, from gmail to Adwords, Adsense. Another example is Tencent, from social network to a mail client, then WeChat, a

Take google for example, from search to gmail, from gmail to Adwords, Adsense. Another example is Tencent, from social network to a mail client, then WeChat, also expanded to games. QQ which is the original social network Tencent was built on, stayed almost the same with or worse with 100x head-counts. It is always a rare event, but when it happens, it is a 1000x win for a company. It is something worth betting on.