Have you actually talked to some of these people who are food insecure? I have yet to find any that are going hungry because of total lack of resources. I've talked to one family who said they never have enough to eat with their $400 per month SNAP benefits. I showed them how they could make sure they had food for every meal with a fraction of their budget and then use the rest for variety and to take advantage of what happens to be on sale. They said, "Yeah but my family doesn't like to eat rice or beans or oatmeal. The stuff we will eat costs about $300 per week."
Other families send their kids to school hungry, but yet have money to spend on lots of other recreational uses (both legal and non-legal). I personally know a family that didn't have enough money for food because they had just spent hundreds of dollars on a new dog and dog food.
If you give people the right to spend their resources as they see fit, some people will spend those resources in ways that prioritize purchases other than food. In other words, if everyone is food secure then it means at least some people are not deciding how to spend their resources for themselves. If you think people should be able to make their own decisions, then you have to accept that some people are going to run out of money for food from time to time.
That isn't to say that there isn't anyone in the US with hard situations that are out of their control, but I have yet to find a family who consistently has no food where it isn't directly related to how they are prioritizing what they do have. I'm not saying they don't exist, but they are a very very small fraction of the numbers you are citing.