This is one of the things that everyone that says Tesla was a con artist miss.
Tesla showed things off to all kinds of groups of people. Many newspaper reported on what they saw him do.
Things like 100 foot long lightening arcs on command.
Ask one of these ivory towered scientists to repeat just that single performance. You will find they can't. They can't even fake it.
Further, the variety and quantity of things he showed... Tesla would have had to work non-stop on building things to fool the public.
Exactly what I sometimes say to disbelievers.
There is no way that Tesla could electrify the ground in all of New York (at his time) if Earth resonance was impossible! Still modern scientists refuse to believe it.