Comment by jasonwatkinspdx

If they can get Starship reliable enough, it'll definitely be successful even if it never goes to mars.

But despite SpaceX's huge successes with Falcon, that doesn't prove they'll cross the finish line with Starship. Falcon and specifically the Merlin engine made just about every choice they could in favor of risk reduction rather than the best possible performance. It was a continuation of work that Tom Mueller did while at TRW.

With Starship they're in more uncharted territory, especially the re-entry concept, and the engine has been designed under the opposite philosophy of trying to push limits.