Getting inside the mind of a terrorist wasn't difficult at all. Even as children, human beings fabricate elaborate revenge fantasies. We're not a particular species. Check out popular video games.
Growing up, I never gave a thought to being a writer. All I ever wanted to be was a traveler and explorer. Science-fiction allowed me to go places that were otherwise inaccessible, which is why I started reading it.
There's certainly more new SF available than when I started writing. That means there's also more bad SF available. Whether there is also more good is a matter for future historians of the field.
We're all nothing but unified arrangements of atoms and particles, drifting around, enjoying consciousness every now and then for a second or so before splitting up to become bits and pieces of trees and stars and french fries.
Living gives you a better understanding of life. I would hope that my characters have become deeper and more rounded personalities. Wider travels have given me considerably greater insight into how cultural differences affect not only people, but politics and art.
Writing allows me the time to travel and see the world, which is what I always wanted to do. I'd really like to have been Sir Richard Francis Burton, but it's the wrong century.
Advances have fallen, generally, for everything except the biggest potential bestsellers. Given all the changes, both economic and technological, SF hasn't done too badly.
I have a bad tendency to get rapidly bored with my own material, so rewriting is hard for me. I mean, I already know the story and would rather read something new.