I graduated H.S. in 2012, so im not too far removed. But generally there are two kinda broad "groups" in high school:

1) Kids who are more extroverted, more "active" in a sense, more wiling to take risks, party, etc...

vs

2) Kids who are more introverted, prefer to play video games with their friends inside, stay within their close "group of friends," less willing to take extreme risks or leave their "comfort zone."

Now these kids who naturally fall into the second group I have described---i.e., kids who "choose" to be boring (to use OP's words) but are perfectly happy that way. This is NOT a problem.

However, the first group I just described... kids who seek to experience as much as possible and want to "live it up" as much as possible. Kids who fall into this group (I feel), if they are deprived of an environment where they can express themselves in a manner that they feel is correct---partying, taking risks and such---then they may "search" for that kind of lifestyle during a period in their life where they probably shouldn't be. Like being a young adult... I can't even tell you how many people I know who are approaching their 30's yet continue to live like they are a kid in high school.

If these kids aren't able to live the kinda life they want to, while growing up, it could lead to feelings like they were "missing out on life" or some other form of inadequacy.

If you don't choose to be boring but are forced into a boring life, then depending on the kid, you may never feel as if you got the teenage "experience," which then could cause developmental issues when maturing into an adult.

Extroverts who are put into an environment where introverts thrive may be more susceptible to mental issues during their formative years.

This is a very complicated issue b/c every kid is different and requires different needs.. there is not blanket answer or solution that is perfectly tailored to everyone's problems.