If the founder(s) had most of their assets in bitcoins (which seems likely unless they were millionaires due to other ventures), it makes sense that they would have sold at least enough of them to still be rich if the price totally collapsed). 

Most people don't put all their money into a single asset - unless that asset has a historical record for stability.

An interesting parallel question: Would you invest in gold or silver if you knew a couple people, who refused to reveal their names, had cornered 20% of the market?