> The end result is that nobody wants to buy or sell shares anymore (since they will get the raw end of the deal) and the market collapses as a result.

Finance noob question here: has this actually happened?

And related, don't non-pro traders basically always lose money on trades but still exist?

(I've been genuinely unsure why insider trading by non-decisionmakers is banned, always seemed like it would result in more accurate prices)