I agree in part. By definition, the conglomerates have many parts. Some of those are not objectively bad.
I also agree that people have choices.
I disagree that it is simply people choice it. When large corporations perform research to find hyperpalatable foods, spend billions on marketing, and capture regulatory apparatus to lock in their dominant position, it absolutely is that they are pushing it on people.
By and large most people don't see any problem with marketing, they will actually get a little bit mad at the suggestion it should be abolished, evidently it fulfills some kind of need for them.
All these kinds of questions you're asking come from a specific way of looking at things that is just not how most normal people look at the world. I'm not saying this out of misanthropy or some kind of wake-up-sheeple attitude, I'm also not saying you're wrong, but when you get knee-deep into critiqueing every aspect of how the world works at some point your worldview divorces from the worldview of most people to the point that "how do they all sleep at night" becomes kind of a moot question.
Those things you said sound evil but they're really not. Finding hyper-palatable food is just another word for finding stuff people want to eat if you're making food, something that's tasty.
Spending billions on marketing? Marketing is how you connect to what customers want. I'm a professional marketer, right and it's really really hard. If I was trying to sell food, I'd try different positioning statements, different ways to see what actually appeals to people. Marketing is not magic; it's market discovery.
And yeah it's bad whenever any company captures regulatory power. That's bad and I agree.