If you could actually compete against fiber I feel like the funding would be very easy to acquire if your first step was linking up the various stock exchanges - those guys pay up the nose for even slight latency decreases.
This isn't going to be lower latency than existing low latency solutions.
EDIT: For more context, the old low latency fiber path between Chicago and New York was under 7ms, and current low latency radio solutions are under 4ms. SpaceX's solution is marketed as being "as low as 25ms".
