> Is venture capital or private equity really uncorrelated to the general stock market?
Somewhat, yes. It's not that it's completely uncorrelated, but it is less correlated than other public companies tend to be.
> It is also difficult to evaluate the volatility of an asset if the price is evaluated infrequently.
Yep, you're absolutely right. This is sometimes called the 'liquidity premium'. People tend to pay less for illiquid assets than liquid assets, all else equal. Which means that investing in illiquid assets should, all else equal, produce better risk-adjusted returns on average over time, especially if you are selling them after they become liquid.
Somewhat, yes. It's not that it's completely uncorrelated, but it is less correlated than other public companies tend to be.
> It is also difficult to evaluate the volatility of an asset if the price is evaluated infrequently.
Yep, you're absolutely right. This is sometimes called the 'liquidity premium'. People tend to pay less for illiquid assets than liquid assets, all else equal. Which means that investing in illiquid assets should, all else equal, produce better risk-adjusted returns on average over time, especially if you are selling them after they become liquid.