What do you think might have been the reason that no adults around helped even though I was still so young?

As I have shared many times that back in 2016, when I was in 11th grade, often some 12th grade boys used to trouble me. One afternoon after school hours, one of the 12th grade boy named Rahul was bothering me and blocking my way. They used to bother me just because I got crush on a 12th grade girl who was one of the senior boy named Anand's girlfriend about a year back when I was in 10th grade. That day I tried to run away as I was in no mood to fight them but suddenly he called that boy Anand and another big built boy named Sandeep both in 12th grade. They cornered me near the school buses. I shoved Rahul like a fool trying to escape which made it worse. Anand tried to beat me but Sandeep stopped him and hold my collar and was verbally abusing me and saying "how dare you even hit a 12th grade boy?" He was shouting and threatening me showing his fist. He was big built so I was scared. Then he threatened me saying "if you again do that to any 12th grade boy I will beat you up." But there were many adults around yet they were only watching instead of helping even though I was only 15 and their junior. They were 16-17 yr olds and there were 3 of them and they were threatening me but still none of the adults around said them anything. Why? I am pretty sure if there was a little boy or a girl of any age they would have helped. I was still only 15 but still why no help?