Here's my take, and you can do with it as you will.

We don't have free will, how could we? We are, as you said, chemicals in a hot dog casing. When I see something I want to eat, it's because chemicals tell me I'm hungry and it will provide sustenance. When I do something that I enjoy, and want to pursue, my brain is receiving chemicals that it enjoys, and tells me to continue doing actions that produce said chemicals. I can choose to do these things or not, but my choice in and of itself is determined by... more chemicals.

But why does it matter, if those chemicals also tell "me" that "me" is the one in charge?

It's like the cave/ shadow metaphor (that I will poorly paraphrase and misuse); hold a chair in front of a candle, show me the shadow, call it a "table" for my entire life, and the first time I see a chair I will say, "so this is what a table looks like!" It doesn't matter that it's actually a chair, just like it doesn't matter if I actually am making my choices. My reality (and your reality) is what I perceive and accept, and nothing more. Logically, I understand that when presented the choice between A and B, my body and the chemicals composing it are the ones "making" the decision, and I'm just acting it out. I get that. But if someone says, "do you want really want to watch The Lord of the Rings again?" I already know that the world has changed, because I feel it in the water, feel it in the earth, and smell it in the air.

And that's my choice, chemicals be damned.