See the unfortunate thing is that it it's both true and not that it's a scam.

Goddard the father of modern rockets came up with this idea too while working on stuff and several others have taken to the idea. The issue generally is cost and I even knew some engineers in university that were working on a vacuum train design at the same time Musk bought the rights to the idea and made a big deal about it.

It was a scam because he didn't intend to do it but to use the excitement of the idea to get funding that he could funnel into his own wealth and stop competing business but the concept itself isn't a scam. Just Musk is and we don't ever have a real conversation about topics because humans suck.