Correct, if you invest billions then you are taking a risk which could either pay off or not depending on whether you're right about that investment being an efficient use of society's resources.

Existing fabs are currently reaping the rewards of their previous wise investments in building out this capacity in the first place right before a shortage. Without those past investments, the shortage today would be even worse. Future rewards will be allocated based on who correctly predicts the best use of current resources to meet future demand (whether that includes huge investments to build even more fabs or not is yet to be discovered).