> Don't the people working for SpaceX deserve to have liquidity?
There is a robust secondary market for SpaceX stock.
There is a robust secondary market for SpaceX stock.
The secondary markets for private securities trade "over the counter" [1]. There is thus no singular "market" which could be said to be the most active. (If you're looking for a more-actionable response, feel free to pop up your email.)
[1] https://en.wikipedia.org/wiki/Over-the-counter_(finance)
(And I was curious whether there was anything like SecondMarket/EquityZen/etc where they're frequently traded in a more standardized fashion)