Yeah and people are over prescribed penacillin, now look at what happened, antibiotic resistant bacteria like MRSA, an incredibly deadly infection that is extremely common to get after a surgery.
Too much aspirin or tylenol will damage your liver to the point you need a transplant, and lowers your pain tollerence significantly if over used. Insulin is not a miracle drug, if you eat the same amount of food and just use insulin to offset the side effects, you'll just die faster with less crashes. Look at Kelly Lenza for this, she's now in heart failure for doing this exact thing because she couldn't put the fork down. Insulin is also used in type 1s, the kind you are born with, not eaten yourself into. A lot of young fatasses might also not have diabetes yet, so again, taking from people that need it.