In the context I provided, I think a wantrepreneur is anyone presenting themselves at a far higher value/position than they are in reality, usually in a matter that is detrimental to others.
I know starting a business is all about "faking it until you make it", but there are tons of braggarts talking about "wielding influence and connections" (because they purchased 20,000 twitter followers) or "becoming a product visionary" (because they hopped on the instagram/twitch/dropshipping bandwagon at the right time and have no redeeming differentiation). Usually these personalities are just annoying, but sometimes these people have hostile intentions.
I personally call myself a wantrepreneur occasionally, as someone who is interested in the culture and community of founders, but who hasn't actually delivered a product yet.