Think of it as having an additional tool in your shed, a really important one: it confers unto you an additional degree of freedom: You can manipulate someone else's state of mind by signalling various faux states of mind of your own (no longer are social signals a tell-culture mandated 1-to-1 mapping, but you can choose whatever input leads to the desired reaction). Social signals and the benefits they confer are sufficiently vague that often you won't find out they were misleading you. Or you may find out ("The last years that person X worked for me I always thought she looked up to and admired me, turns out she always just pretended so she could keep the job!"), but the defector already reaped the (transient in time) rewards. Nothing is forever, the traitor can milk you like a gullible cow (or a gullicalf, living in California) then leave, harm done.