Step 3 != profit

Or do what Sociopathic Oligarchs do, and put it into Cheat Mode, make a ton of money, then use your money to change the rules so nobody else can use Cheat Mode.

Insulin is only a part of the treatment/cost, and most of us are on several different types (fast-acting/long-acting). If you're on a pump, it's usually just fast-acting, but pumps are expensive. There's also monitoring devices like glucose monitors and test strips, which are pricey. The sensors for continuous glucose monitors are about $100 a piece without insurance and last a week or two. Glucagon is a pretty useful thing to have on hand if you're on insulin. It's like Narcan for insulin, and it's not inexpensive. There's also that little matter of increased doctor's office visits and frequent bloodwork, even with insurance, the copays and deductables can be burdensome. They won't write the script if you don't show up regularly. My diabetes doesn't cost as much as my food, but it's close, and I have decent insurance. All of that, and you're still likely to have complications to some degree in your old age. Nothing about having diabetes is reasonable- universal healthcare would make the pill easier to swallow though.