He will cling to his fantasies (Harari)

As long as he fought imaginary giants, Don Quixote was just play-acting, but once he actually kills somebody, he will cling to his fantasies for all he is worth, because they are the only thing giving meaning to his terrible crime. Paradoxically, the more sacrifices we make for an imaginary story, the stronger the story becomes, because we desperately want to give meaning to these sacrifices and to the suffering we have caused.

Yuval Noah Harari, Homo Deus:  A Brief History of Tomorrow