One has to wonder about the idea of having a hidden or unconscious death wish, the Thanatos as per the Greek god, or holding the seeds of one's own destruction as I would call it. It is just a speculation. They may not be very happy with life inwardly.
Although some scientists debate it, Freud thought of it this way:
According to Sigmund Freud, humans have a life instinctwhich he named "Eros"and a death drive, which is commonly called (though not by Freud himself) "Thanatos". This postulated death drive allegedly compels humans to engage in risky and self-destructive acts that could lead to their own death. Behaviors such as thrill seeking and aggression are viewed as actions which stem from this Thanatos instinct.
About Thanatos:
The god's character is established by Hesiod in the following passage of the Theogony:
And there the children of dark Night have their dwellings, Sleep and Death, awful gods. The glowing Sun never looks upon them with his beams, neither as he goes up into heaven, nor as he comes down from heaven. And the former of them roams peacefully over the earth and the sea's broad back and is kindly to men; but the other has a heart of iron, and his spirit within him is pitiless as bronze: whomsoever of men he has once seized he holds fast: and he is hateful even to the deathless gods.[7]
https://en.wikipedia.org/wiki/Thanatos