There's two different groups here - Suicidal people who take others out with them, and murderous people who commit suicide, often indirectly, in the process of murdering.
I think the second group generally kills people who they have a specific motive to kill, or they kill people as a means to achieve notoriety and posthumous fame. But in both cases, they're specifically making a spectacle of it - School shootings being a sadly frequent example.
But I don't think the Air India pilot was in that group. I think that group is more motivated by anger than by depression. Like you said, they're avoiding the consequences. And while a plane crash is certainly a spectacle, I think usually that latter group wants to take out more specific groups of people than just the random 200-some people who got on their airplane. I would also expect them to have either left a manifesto or said something on the CVR.
So, I'd posit that the captain was in the former group, and his pain was all-consuming enough that he didn't consider the effects on the families of his passengers.
Just that your examples of people who didn't do it because of thoughts about their family, or who tried and failed and were thinking of their family in how they did their attempt, are the ones who lived to tell you their stories. It may well be that the people within your extended circles who get to the level of no longer thinking about others are the ones who didn't live to tell their story.
EDIT: Sorry, I realized I used the wrong term. I meant
survivorship bias.