Hey fellow human, you got a tough one there.

Let me preface my answer with saying that your situation hits very close to home, but this is such a personal question that I have a bit of a hard time answering.

Me: Studied business at one of the top 3 schools in a large EU country, but the choice was more about utility rather than passion. Graduated fine with 24.

Huge passion since teenage days was Biology in my case. I thought about breaking off my business studies more than once, but pulled through given the rank of the school I was in.

I faced the exact same question as you did: Back to school or not. Talked to my parents about it, they even covered me and told me they'd support me in my choice. Ultimately I decided against it.

Now here's the trickiest part that can be underlined with anecdotes but it's still not a solution for you: Those two options were really hard trade offs. And for me, this tradeoff continues to be a struggle.

Around the time I had to decide I had already gotten into Data Analytics/ Data Science (though softer given the business degree) and saw myself pursuing a career in these fields. I also knew a thing or two about Biology studies and job prospects (severe lack of research positions, possibly even more so than physics, horrible pay, and the crushing rigidity of the academic system paired with complete dependence on a small circle of people in case of graduate/ PhD studies). Around the time I was in a relationship with an older girl who was in the midst of her PhD and whitnessed this system and supervisor induced depression in her first hand.

So I kind of framed my decision as a trade off: Either, I could opt for business, significantly increase my lifetime earnings, try to engage in fascinating subjects in the data space and network in this area with other peers, but risk being down or depressed in the long run for never experiencing "the real thing" of a STEM-ish education. Or go for the degree which would very much lower my LFTE but likely be intellectually very rewarding and open the world of academic networking to me, but also incurring the high risk of facing depressive situations for the duration of the studies.

And this tradeoff has pretty much persisted for me. I am turning 30 this year. I have been successful in my field such that I was able to significantly increase my earnings over the past years as a freelancer. I have grown tremendously as a person in many ways. But money, as David Foster Wallace noted in his graduation speech, is a futile value to pursue. I am bitter and depressed about never having tried the other side at the same time.

It's not fun. I can hardly connect about the topics in the data field with my business alumni. That immediately lowers the value of networking for everyone involved and has led to a degree of distance between me and many of them. I do experience very intense and instant depressive episodes sometimes when attending academic events or reading about academic figures who did meaningful research advancing their field. The thought of not only having had the chance to do such research myself, but to be part of the ecosystem that is academia... - I can hardly put the intensity of the sadness into words. It never lasts long, though and I have not become a depressed hermit in general.

I am fully aware that I might tell you the same story from the other side had I chosen the degree. Other forms of sadness, other regrets.

It's impossible I feel to tell you what to do. It all depends on your unique context, your unique values. All I can say is that you should not rush the decision and try to put your emotions out of it as much as you want. Meaning write a list with pros and cons, talk to people you know and ultimately follow your gut. It will never be an easy decision, but you'll have to live with the trade off you choose.

By the way, I had other classmates in my business degree who were 27 during our first semester. Another classmate of mine went into med school after our degree, he is still studying now. If there is one thing I feel certain about saying: Do not factor in age as a primary factor or social rule to consider.

It is your life, it's your decisions and there have been countless people who studied well past your desired age.
Do what makes you happy the most, i.e. you can best live with.