I’m not sure why you’d think sugar isn’t addictive. Whole books have been written on that subject. They know for a fact it is addictive, and I know people who crave it horribly. And it’s usually the exact opposite, the more you eat the more you want to eat. You’re right we do need glucose to survive, but you can eat/drink too much of anything, including water.
I know a woman who is so addicted to sugar, if she doesn’t eat it for a day she goes through full-blown withdrawal symptoms. And based on the rest of her diet, she’s getting plenty of carbs and calories where she isn’t starved or anything.