[didntcheck]

Putting aside the more sociological arguments about (non-)human nature for a second - roughly speaking, technological development = ability to wield greater amounts of energy. The easier it is to put a satellite in orbit, the easier it is land a missile on another country. The easier it is to harness virtually free energy, the easier it is to rain unimaginable destruction on your enemies. Robot workforces enable robot armies (directed by malicious humans, not Skynet)

The more widely accessible a technology becomes, the more damage a single person or faction can do, and therefore the probability of someone causing mayhem tends to 1. And it's basically always less effort to destroy something than (re)create it

We can hope defensive counterparts to all these risks develop at a greater rate, but I don't think that's a given at all

Also remember that from a SETI/Fermi/Great Filter perspective it doesn't matter whether the species completely kills itself off. It could instead just repeatedly reset itself to steam age technology, and therefore never be stable enough for long enough to become seriously spacefaring