"the bank of middle-class parents" is not a real bank. It's your parents. You can pay them whenever (and you most likely never fully/really will, and that's ok). Your opportunity cost might be true and might be "I can't help support my family on a part time job".
Your situation might not be extremely rarefied, but I don't think you grasp the immensely insurmountable advantage you have in this scenario.
I coasted through five years of college ... Compared to a 9-5 job, yeah, college was a five year vacation.
If you went to college voluntarily and did not care about neither the monetary constraints nor the opportunity costs, then sure that's a vacation. I suspect pretty much anything can be framed as such under those circumstances. For most people, this is not actually a realistic option.
Your situation might not be extremely rarefied, but I don't think you grasp the immensely insurmountable advantage you have in this scenario.