Are mean kids the problem for bullying or because kids dont fight back?

Alright so I went through elementary, junior high, and high school and kids would make fun of me all the time as i wasnt the "coolest" kid. I wasnt a loner or a quote on quote "nerd" but i was i guess ugly and a total twig lol. The thing is, i didnt let those little pricks get through to me, right when they say something about me, I'd push them or talk shit right back. I was raised to not allow people to bitch you around so this was just natural for me. Now to my point, I believe bullying is a problem because many parents, teachers, and other figures of authority now days teach kids to simply "ignore" the bully. In my opinion this only builds up those bad vibes causing the kid to get to a breaking point after their brain is constantly just being filled with all these bad memories. Over time these memories just build on top of eachother and cause anger, hatred and depression. This also could be the biggest reason kids shoot up schools. Because no one has respected them evee because they never stood up for them selves and now, they're really going to show these bullies who "should be respected". I remember in school being taught that if someone hit me to simply go tell a teacher and that if i hit back, I'd get in the same trouble........ That doesn't make any fucking sense. Number one, if you go tattle tale like that you're going to get bullies even MORE for being a "snitch" or "pussy". Ive been raised to stick up for myself. Even though I was a little twig, literally like 6,2 120 pounds lol, if the biggest kid in class pushed me over a desk im coming back and atleast trying to beat his ass whether it ends with me getting the shit beat out of me or not. As far as i know school shootings werent a problem until recently when kids have been taught to "ignore" the bully. Ill compare this to procrascination of an essay. You have a 10 page essay due in one month and wait till the last day to finally face your problem. Now its a lot harder to do that task because you're stressed, anxious, etc. Hopefully you all understand my point. Im open to new ideas, please comment below your stories, feelings, etc. I just want an open discussion on this topic and started with my feelings on the situation!