Going to ignore the flat earth comment as that has no bearing in this conversation.
Brightline stopped selling their "annual pass" in order to accommodate demand from just the Miami to Orlando leg, so there's more than enough demand out there for Brightline. When Brightline first opened the Miami-West Palm leg, people questioned the profitability of such a run when it was "only" an hour away driving... and it was well attended and obviously a success as the company continues to invest into adding more stations along the current route (Fort Pierce, Cocoa, etc.), let alone pursuing Tampa.