It is disappointing philosophically but I would imagine how the game theory of this works out strategically if really trying to play an optimal strategy is "always cheat".

There just such asymmetry between the risks vs payouts.

Sadly, I imagine your professor was simply wrong. Most likely even for you there is something you could cheat/lie about that would be practically undetectable and give a huge payout for almost no risk.

This is also why a level of a self delusion is an advantage in our system too. Then you get the benefits of cheating/lies without even knowing it or having to intentionally cheat/lie.

"Cheating ultimately cheats oneself" sounds right but just isn't reality.