I have experience with this, albeit it’s a bit different. In undergrad, my classmates’ families were on average more affluent than mine, but the gap wasn’t quite so wide for most people. (My freshman year roommate’s family was quite wealthy; she grew up with a housekeeper and didn’t know how to work the washer and dryer. I loved her!) Graduate school was where the real differences were - I went to an Ivy and some of my friends were famous supermodels, politician’s children, offspring of fancy executives and the like. I was usually the person from the poorest background in most rooms, and I grew up working-class, not dirt poor.
Worrying about feeling like an outcast or not being able to afford things is a real worry, and it will happen. In undergrad, I spent my spring breaks working or staying at home when most of my friends took beach trips. I did work in college and did have to answer (or roll my eyes) at some well-meaning but ignorant questions about why I worked. It was customary for juniors and seniors to move off-campus, but since I could afford neither an off-campus apartment nor a car, I was stuck on campus. (That’s not as big of a deal if people like you, though; it wasn’t difficult for me to get rides to events or house parties.) My summer internships and jobs were definitely less glamorous than most of my friends’; I needed money, so I didn’t have the option of taking an unpaid internship and did not have the connections some of my classmates had.
In graduate school, similar things happened - a friend of mine got married in India and I couldn’t afford the visa, much less the travel. (In hindsight, I wish I had borrowed, begged, and stole to go to that one.) There were definitely small things I had to miss out on too, and occasions when I went and ordered one drink and a salad and hoped nothing bad would happen between then and my next paycheck. Graduate school brought other things - me and a bunch of my cohort mates got married around the same time, and the difference between their weddings and my wedding was staggering. (And aquapt is right - the milieu makes a difference. I went to graduate school in New York, so the disparity could seem much larger, since there were way more fancy restaurants and events to go to. You wouldn’t notice it as much in, say, West Lafayette or South Bend.)
On the other hand, though, I was exposed to thinking and dreaming about a level of achievement I would’ve NEVER thought of had I only went to school with others who had incomes similar to mine. It’s a funny thing, what effect your peers’ goals and ambitions have on you. You start to realize that you are just as intelligent and capable as your classmates, and if they can aspire to be MBB consultants or Supreme Court justices or Ivy League professors or whatever, you can too! And honestly, that upgrade in your ambitions for yourself is WAY more important than missing out on the occasional concert or trip. And I learned some skills that I wouldn’t have learned if I stayed with only people from my income group - things like how to eat with chopsticks, how to behave at a wine and cheese shindig, how to eat at a party with multiple forks and spoons and cloth napkins, that there are things called “stocks” that you can invest your money into, etc. These are skills that actually have come in really handy in my current career/life, as I’m in a totally different socioeconomic status than my parents were (or are).
And actually, some of the experience is about building those connections. What if one of your classmates’ parents is the CEO of a company you want to work for, or a semi-famous journalist in your region, or a former president? (No seriously, the daughter of a past president was one of my classmates in graduate school! Her father gave the commencement address for our school :D) That’s not even mentioning the alumni connections…a sitting president came to give the commencement address for a school in the university a different year.