In ten years, given the rate of social change, everything I do today will likely be considered outmoded, backwards and probably contemptible.
In our increasingly atheistic society, even if I have a negative impact on history, I will likely be unpunished.
If I wanted to make myself a legacy, and had suicidal tendencies, the shortest path into the history books is clearly a destructive one.
Cue Kevin Tillman: "He's not with god; he's ..."
Yet that rarely stops anyone from pursuing purpose or meaning, and for the ambitious, a legacy of any sort is the closest they'll ever be to reaching immortality, or relevance beyond their immediate sphere of influence. If you're purposeless, why shouldn't your decisions echo throughout history, and make you moderately less so on a less cosmic scale?
Nihilism is an outgrowth of atheistic convictions, when adopted without a supplemental normative framemework that prescribes and justifies a system of values, or when adopted by the depressed or otherwise mentally ailing.
I've seen no coherent argument that life should be considered sacred in the face of a universe devoid of meaning or purpose, whether one's own or that of others. The concept is hardly a cure for nihilism. Offering it as a more legitimate alternative simply because it's more comfortable or reassuring to many people occupying a nihilistic space.
I should also mention that this guy, with everything taken from him, made to feel completely insignificant, was able to save maybe a few lives, and he'll never know about it.
And whereas boomers tended to indulge in wanton hedonism, or pursuit of commercial gain to try and feel a sense of purpose (think midlife crisis, "the one with the most toys wins", etc), millenials and later have seen that that doesn't work just by watching their parents (and oftentimes either already experienced it, or don't see it as a possibility), and so are trying something different (though something also tried, historically). Oftentimes symbolic acts that will leave an impression on others; that at least makes their existence matter -to someone-, even if it's negative.
I remember being in school during Columbine, and a comment another kid made at the time struck me - "If I was suicidal, I'd want to go out with a bang too; at least leave a mark". He was under no belief that his name would be remembered, but he wanted to at least -make a difference- before he was gone.