That's the problem, though. Some Zefram Cochrane figures out how to work subspace, but all the profit from antigrav sleds will go to whoever won the patents for

That's the problem, though. Some Zefram Cochrane figures out how to work subspace, but all the profit from antigrav sleds will go to whoever won the patents for a pallet mounted on a quadcopter 40 years earlier. (Star Trek avoided this fate by having World War 3 happening in between today and warp drive.)