It doesn't matter is he's the only one. He's the one we're talking about right now. Comments like yours read to me as "well everyone is doing it" and I really don't like how this serves to normalize bad action. Trump makes this rhetorical move all the time to justify his own corruption.
Your reply of "everyone is doing it" definitely could a logical answer to the question of "Why is Musk allowed to be worth half a trillion dollars again?" instead of just a moral justification.
I would agree that Tesla's stock price is as high as it is because investors are betting that there are plenty of other suckers who will be convinced by Musk's unfounded claims.