> [...] insiders are incentivized to wait until just before the event to make their trade, [...]

What are you basing that one? And how is this supposed to work?

If you are an insider the incentive is to trade as soon as possible, lest some other insider beats you to the punch, or some conventional leak (or investigative journalist) spoils your party.

This is easiest to see, when there are multiple unconnected insiders: the first to trade wins. But even if you merely suspect another insider might exist, you have an incentive to trade first.

> And that's assuming that you can distinguish an insider from someone lying for the sake of market manipulation.

That's exactly the same as any other noise trader in financial markets, yes. Nothing specific about insider information.