You might also want to look at why other people's happens or success makes you feel bad. It's a very common feeling but it's unhealthy and a sign that you have poor self-esteem.
That may be true, but poor self-esteem is dramatically more common among young/developing people trying to figure out their place in the world. There are plenty of exceptions to that in both ways (young people with great self-esteem, older people without it), but I think that kids/teenagers will always be uniquely susceptible to ego "body blows" of the sort that social media makes very easy to receive.
You might also want to look at why other people's happens or success makes you feel bad. It's a very common feeling but it's unhealthy and a sign that you have poor self-esteem.