Not at all.

If Zuckerberg had told the Winklevi he planned to quit and start a competing site, then there would have been no lawsuit. The harm was intentionally misleading them, so they wouldn't find a replacement programmer to finish their own site.

Your best bet is to be aboveboard, and get people to sign off on whatever they agree to, so they can't come back later with a changed story.

Well, they settled. I think they were arguing that they had an implied contract with Zuck, not (primarily) that he stole their idea.

IIRC they didn't win it, it was settled out of court. If you believe the standard line, it was settled to avoid the random chance that a civil jury would decide based on emotion rather than merit.