Could a SpaceX constellation provide lower latency than undersea fiber? If the satellites can communicate to each other would the speed of signalling through a

Could a SpaceX constellation provide lower latency than undersea fiber? If the satellites can communicate to each other would the speed of signalling through a vacuum/air (~30% greater than fiber) outweigh any other steps? If so, maybe SpaceX should get into HFT/arbitrage between global markets?