In 1981, Microsoft raised $2.5 million from the VC firm Technology Venture Investors, at a $50 million valuation. Its revenues were $40 million. (Current dollars.)

In May 2011, AirBnB raised a VC round. Like Microsoft, it had large and fast-growing revenues ($25 million). Its valuation, however, was higher. A lot higher. Over $1 billion, more than twenty times as much.

What changed?