Insider trading is an artificial crime. Top executives are never indicted, even though they trade on inside information all the time. They allow prosecutors to use this regulation only so long as prosecutors are careful to punish relatively-clueless minor defectors from the ongoing conspiracy of corporate executives against the investing public.

Think about the results of "inside" trading. Information that was previously the sole property of insiders is released, through its effect on the prices of securities, to the public at large. This is a good thing for the public. It is a bad thing only for executives who haven't completed the trading schemes they've based on that information.