By that logic, why couldn’t someone have done the same with electric cars and rockets? Were we never going to go into space again? Did the Nissan Leaf not already exist?
Launching Google was a low stakes endeavour. Nobody was willing to put as much on the line as Musk did with SpaceX and Tesla. It's likely all of it would have happened at some point, but certainly not as quickly and effectively as it has thanks to Musk.
In the 20+ years Google has dominated search, who has come along and iterated a “better” version? Bing? Is the capital and scope required not approachable, as you suggest?
Similarly, since Tesla helped demonstrate a valid market for electric cars, how many automakers have released competitive (and to some, better) EVs? If the capital requirements and scope were too large, where did Rivian and Polestar and numerous other upstarts come from?
That is first movers advantage that gives rise to a network effect which acts as a powerful moat for a natural monopoly. Another search company could have been google without the need of a crazy person. Which is to say a google like company was probability inevitable, if not google then something like it.
Re SpaceX: it had massive government funds going for it. So surely, no one else could do it, because they don’t have the funds to lobby for taxpayer money that hard.
I still think we should have just given it to NASA, a private entity has no business in space.