Without the investment and PR explosion he gave them it is incredibly unlikely they could've made it this far. The legislative hurdles and competitive pressure Musk just shrugged off for years should not be discounted. He had his entire fortune to fall back on if the gamble didn't pay off, so the threats to his bottomline and prolonged battles did not impact him the same way it would a startup.
Again, I can't stand the dude. But Tesla made it because of him, warts and all.