Aside from sarcasm, which invites opposition, I think you've touched on a taboo subject. I think what you say is true. At the same time I'd wager that a disproportionate number of founders have bipolar 2 tendencies, which will provide fuel and context to depressive episodes. If both are true, it becomes very tricky to determine cause. It becomes easier to focus on those potential causes which are outside our control, that depression is something that happens "to" us. Of course this is often the case where there is a medical issue, but as you point out, it is also often a result of circumstances and our reaction to them. Or even more confusingly of course, both.

Getting back to the original comment and how it was received, at the beginning of your comment you make a claim that is going to be controversial. From that point on, any introduction of sarcasm will push anyone not allied with your view towards open hostility.