Even if they did believe in the possibilities, they are likely eager to offload in favor of a more diversified investment strategy.
Most folks I know that even think their company is in decent enough shape sell off RSUs quick as they can because they broadly don't trust having a bunch in a single company stock. Especially if that stock collapsing would likely correlate with them losing their paycheck too.
The existing network will be gone within a few years. By design. If all goes well for SpaceX, it will have been replaced by a new network, which will also be gone within a few years.
Just pointing out that the existing network can't be relied upon without continued re-investment constantly. It's hard to build up a strong first mover advantage when the fruits of the effort burn up in the atmosphere routinely.