Two areas to highlight the point:
- High-energy anything. There's a saying that any propulsion system that could allow us to travel between planets in a reasonable (for human) timespan is also a weapon of mass destruction. And it's not just space travel - history of technology in general is about getting, storing and making use of bigger and bigger quantities of energy.
- Self-replicating system. The best-known example of these is also known as "biology". Something we're only beginning to play with on a serious level. Mishaps, or worse - deliberate malicious actors by crazy individuals - could have planet-wide consequences as our ability to manipulate biological nanomachines grows.
Sleep tight :).
(Also, alt-text from https://xkcd.com/728/ - "Maybe we're all gonna die, but we're gonna die in really cool ways.")