ruined what? The whole point of this story is that the uncle "ruined" his own life never realizing it.
In his eyes, he is living a complete life without missing anything. In most other people's eyes: WTF?
I'm just here to see how bad it gets.
NOPE, you're the one missing the point. The dude is living in a world where most people think he isn't even human, so he rejects everyone to a degree. He also escaped to video games at a young age so he's not very aware of real-life "Event Flags". His life was far from complete before or after he transferred to isekai land. It's honestly only now one can say he has a life that's "complete" with his nephew and his girlfriend hanging out with him. Of course, even that might be pushing it.