I should note, there are some really great things about uni and overall, I prefer uni to high school. Those are just the things I do miss.
In uni you get much more freedom and you can figure out for yourself what you want to do and what you need to do. If you know a lecture is going to be pointless and horrible, you can just not go, and you don't have to answer pages and pages of questions about it. You can also pick what topics you like best in a course and do an essay or an assignment on it and really go into it deeply. I guess also, being exposed to people who are really clever also gives you an incentive to improve, and in that way is a good thing.
I don't think I'll experience the big fish small pond thing again, at least not until I get into my chosen career (whatever that is) and even then, it'll take awhile and it isn't guaranteed. But it's okay. It's actually really relieving to figure out that it's okay to be average or above average. And it's fine if you don't accomplish something that other people think is remarkable, as long as you are enjoying what you're doing and you are being the best you can. You don't have to live up to external standards of awesomeness.