One reason you'd presume Ruby found university less enjoyable and still clings onto her schooldays and goes back there, despite leaving over 4 years ago is because you get constant validation and praise at school. You work hard, teachers single you out and shower you with praise, you get top grades and everyone says how amazing you are. There are school reports, awards, assemblies that all put the intelligent/hardworking kids on a pedestal, thus making them feel special and increasing your ego.
You don't get that at uni. You sit in a lecture theatre with hundreds of other students, write your essays and have it anonymously marked a few weeks later. Most lectures won't even know your name (even with Ruby's constant bombardments of emails and thank you cards). In the real world, you don't get praised for doing tasks and work; it sets you up for the real world and that environment.
As for good grades, you realise the further you go up the ladder how meaningless they are. GCSEs feel like the most important milestone of your life when you're 16, but you sit them and then realise that absolutely nobody cares. Ditto A-Levels when you go to uni. Most of these Studytubers built their whole self-worth and brand over good grades and being high achievers at school. It would be disingenuous to say good grades are meaningless, but the frank truth is they don't define you and all the opportunities you'll get in life. Ruby didn't realise that and that's why she's not well rounded. She's got a first from a Russell Group uni; as her graduation showed her, 100s of other students achieved that exact same accomplishment, while getting involved with uni life and having an active social life, making them 10x more employable.