I'm going to stand up at a concert while the people behind us keep asking us to sit down
What is your reason for intentionally trying to do that at a concert?
I just want to be able to see the concert better.
It is rude to ruin someone else's paid experience. If you want a different seat you should purchase a different one higher up.
It's fine, I got the best seat thanks to my free will. I didn't hurt anyone and I'm glad I did it.
Blocking the view of someone else just so you can have a better view is very selfish. You can have a good view while sitting down as well so it would be a lot more considerate for you to remain in your seat.