I totally know where you are. I worked three jobs during college to help pay tuition and took out thousands of dollars in student loans which I'm still paying back now. My advice would be talking to your school's financial aid office, and trying to find any types of grants or scholarships that you might qualify for. And also have confidence in yourself that you'll be able to pay back your student loans. And don't be afraid of taking more on.
Most student loans have reasonable repayment schedules.
And offer many different types of repayment plans. I would suggest talking to a career counselor who could possibly set you up with a mentor. Someone else who has started up a business, ideally around your age. And just pick the counselor's and the mentor's brains for specific information about starting your own business. As for convincing friends that you are not crazy.