If we look at this chart by Ben-Ami Scharfstein which compares all the important philosophers of the West and compares them in terms of how suicidal they were, we see that Kant above all the rest is immensely suicidal. He’s a hypochondriac; he’s fearful of inherited illness; he’s depressive; he never married and he’s the most suicidal.
One philosopher not on the chart is Albert Camus, who, from reading the Le Myth de Sisyphe, we know that although he is completely absurd, is not in fact suicidal. Or at least proclaims not to be. There aren’t any reasons for Camus to commit suicide and so he lives out reason’s fundamental contradictions. On the other hand, Kant, whose Kritik der reinen Vernunft demonstrated the contradictions of reason, was nonetheless committed to the completeness of reason. I think Kant knew this was fallacious, as Gödel’s incompleteness theorem in logic had shown in the 20th Century. There is no “royal road” onto which reason can create foundations for all the sciences, mathematics and logic. I think Kant knew his project was committing “philosophical suicide” as Camus said about it, eventually leading Kant himself to feel suicidal since his identity was based on such a grandiose project.