I think he is somewhat right. I do not think you can go directly after large markets. Most successful companies have gone for small markets that then disrupted large markets. I'm (100M exits are not that great for the record!).
You clearly don't understand VC or Private Equity very well. 15 mil is chump change for Sequoia. Sure they would rather not lose it but 43 million is not a "huge amount of cash" in the VC world. They probably just got back a 1x or 2x return and that is about it.