It's not uncommon to meet would-be software entrepreneurs with stars in their eyes. This number crunching from Aileen Lee does a good job of showing just how difficult serious software success is. The focus is on the so-called "Unicorn Club", US-based software companies started since 2003 and valued at over $1 billion by public or private market investors.

The reality check: only 0.07% of venture-backed consumer and enterprise software startups make it this far.