Stop right there. You haven't added anything substantive to support your "but". And saying that you'd trust John Carmack to solve technical problems is pointless. If John Carmack was on your team, you'd get funding even if your startup was about making cupcakes. The probability that you have someone at the very top of their field is extremely low.
Finding someone who can solve the technical programs of your game may not be a huge deal, but gameplay and creative both give you massive amounts of rope to hang yourself with. Moreover, they can completely upend all the work you've done if things don't pan out. This isn't quite like the web startup world, where if you've got a decent amount of sense, you can predict what will be useful, release a minimal version and iterate post-launch.