Being extremely self-centred didn't cause my Complex PTSD. Being extremely self-centred didn't cause my debilitating disabilities. Being extremely self-centred didn't cause my chronic fatigue, chronic pain or chronic illnesses.
Honestly, this is similar to anti-choice, guilt-tripping, victim-blaming rhetoric many of us already encounter from medical professionals, loved ones and society: "Suicide is selfish", "Life could be worse", "There are other people who suffer more than you."
Even if it is true that life could be worse or that someone else is in an objectively more dire situation, it's a moot point and an asinine way of invalidating someone else's experiences, feelings and reality. It is similar to gaslighting, to saying "Things aren't that bad." The irony is that those who say such trite tripe rarely comprehend the full circumstances of the person they are invalidating.
Other people's problems do not stop us from struggling with our own. Struggling can result in turning our focus inwards, but that is a natural consequence of unbearable pain. Suffering is not selfish - it is unendurable torment. Expecting people, however, to preserve their lives at all costs regardless of its quality is selfish. Expecting people to find solace in the suffering of others because life could be worse is selfish. Invalidating, ostracizing and silencing suicidal people is selfish.
Society is far more careless, narcissistic and self-absorbed than suicidal individuals could ever be.