Their stock is the same class as the founders. Everyone who had options in Slide also made money proportionate to Levchin, which is better than the investors did, who made nothing. (This assumes early, cheap options. Later ones may have lost money and be worthless.)

The situation the OP is referring to is when the founder decides not to sell the company or IPO, or makes a poor decision about when. With the former, there is no liquidity and stock in a private company with no liquidity or profit sharing is pretty useless.

If a company takes VC investment, it is basically committing to sell or IPO at some point (VC wants control to ensure this), ensuring the options will at some point be liquid. So, technically, having a VC with board control could be a good thing in some situations to ensure that the founder doesn't get any ideas about building a "lifestyle" company and that everyone gets a payday at some point.