FTOP, really either/or?

[PlayerA]

FTOP basically states that if your opponently would play differently if they saw your cards, you gain. If they would play the same, you lose.

I think that it's not really so clear cut. I understand that poker is a zero-sum game (minus the rake). However, consider a situation in Hold'em where 10 people see the flop for 1 big blind. One player flops TPTK and another flops nut flush draw. Everyone else flops nothing and drops (of course this is contrived but bear with me). Now, TPTK is correct to bet and nut flush draw is correct to call. I contend that both players don't really lose anything at the expense of each other just because they would play the same if they saw each other's cards. What has happened here is that both players have gained at the expense of the other 8 players.

So, what about those cases where both players play the same if they see each other's cards? Where does that fit? Am I supposed to use the search function?