If a company tanks right after being listed on the public markets -- that is, right after insiders got an opportunity to dump their shares on less informed investors -- most likely a serious financial crime has taken place. A real business doesn't go from a 47bn market cap to zero in ~2 years. It's not sufficient to make generic disclosures to investors that there are substantial risks and that you have an unproven business model and such. If it looks, talks, and walks like a pump & dump scheme it probably is.
It’s not self dealing if everyone is on the same page. Neumann didn’t hide any of this. From SoftBank. From the public.