> Yes this is just survivorship bias.

If you're looking for insiders it's generally helpful to start with the "survivors". Not because insiders can't lose but because winning insiders are those effectively exploiting their unfair knowledge. You need filters, so concentrate on the worst offenders first.

Of course, not all winners are insiders. You still need to filter more, but it's definitely the first filter. Big winners are the second, for the same reason: scale of exploitation.