[QuesnayJr]

I think the message of the book is more complex than that. The character who sets up the MAD situation spends half of the book having already given up, before discovering the MAD solution. At the same time, Earth pursues a straightforward military strategy of building a large space fleet to stop the Trisolarians, but are unable to anticipate the aliens' superior technology makes their efforts futile.

Ultimately, Earth sends the MAD signal, and ends up destroyed. The goal of the artificially installed defeatism was to make humanity flee the Earth, and it's only the those who fled the Earth who survive its destruction.