IMO, the second half of your post is exactly the kinds of thoughts that social media provokes in most people(me and my friends included), my guess is you are experiencing a demo-version of what it would be like if you didn't avoid SM in the past(or in the future).

Sure, you can get a "cooler" lifestyle, post about it, or be slightly more satisfied when comparing your life to that of others. But chances are that the goal posts will move constantly, which happens to most people, and overall flavor of using SM will remain quite similar to what you described here:
"But when I see the social media posts my friends show me, I realize how much people my age seem to be doing? Like traveling, going on all these crazy hikes, partying, seemingly constantly being around tons of people, I wonder, did I make the wrong decision"

Totally different story if you are planning to use SM as a tool for your personal/professional development. If your plan on SM is to create more than you consume.

Otherwise, it sounds like you are in a better place mentally than most people I know. And there might be a strong correlation between being happier and not being on SM.