Everyone is taking my chewing gums 😭

I’m 17f in 12th grade preparing for NEET, studying at a local residential coaching center where only a very few students are day scholars, and I’m one of them. I take chewing gum to class to stay awake. Let’s say I have 2 pieces every day, and every time I open my bag to take one, at least 10 girls ask me for some. This means I have to go to the shop frequently to buy more gums The real problem isn’t just that,it’s also the money. This has been going on for over two months now, and I’ve spent more than 1000 Rs on gums for others. Only one girl paid me to get a bunch of gums for her. while the rest just ask for it. When I tell them I have less gums today, they look at me like I’m being selfish and intentionally bringing less gums with me to avoid giving them. Yes i am, cause i don't know what else to do. Am i being too big of a cheap skate? Too petty? Is this something I should overlook?My family is financially decent but I still don't think i should spend their hard earned money so casually on others because we are not filthy rich or anything. Just tell me if I am right or wrong and how to go about this situation after that 😭Tbh if i tell them no even in a subtle way, they will still understand my intentions and probably will start being less friendlier with me after that. I don't really have any friends in my class. Actually no one does. They selected 15 of us into a different section and most of our best friends are in other sections. The problem is no one wants a bestfriend like I do here, everyone is so individualistic. It's just 15 girls anyways so all of us do everything together as a big group of friends. So, if i deny them anything,I will probably be seen less of a friend from here on. They selected 15 of us into a different section and most of our best friends are in other sections. The problem is no one wants a new bestfriend here like I do, everyone is so individualistic. It's just 15 girls anyways so all of us do everything together as a big friends group. So if i deny, they will probably stop being close with me. Yes i do realise that they are not "real" friends but I need them. for example, when suddenly a lecturer takes an emergency class in the evenings and I am at home, one of them has to call me so that I can rush to the class. they are so many things like this and being alone here is just not really easily at all.