One doesn't need to be able to point to a specific thing which they invented while alone in their garage with no help from anyone else in order to be a remarkable person. Elon is intimately involved in the minutae of SpaceX engineering and damn, if landing orbital rockets on a floating barge isn't impressive enough for you, I don't know what is.
The meat of the claim is "just an engineer [...] Did he invent something that I'm not aware of?"
The money isn't mentioned to disqualify him, but to point out that money isn't enough.
What did he actually do that shows genius?