That's a weak argument. The reason some of us don't believe that consciousness is something else than the state of a brain following physical processes is that the latter is a much simpler theory and matches every objective observation we can make.

If you try to explain consciousness as just the state of a physical brain, all the observations agree with you. The brain is known to be capable of computing. There are known regions inside it that activate when the subject feels certain emotions and thinks a certain kind of thoughts. There are regions that have predictable effects on the person's consciousness when damaged (see lobotomy). _And_ this hypothesis doesn't contradict any observations made until now (which is not the only argument as you're implying, just one of them, and a good one).

If you try to explain consciousness as something else, you have to change the laws of physics. You have to consider that _something_ exists that isn't in the current theories, just to explain a phenomenon that shows no evidence of needing that. There's no data to guess what it is, how it behaves, why it exists, whether it interacts with anything. Actually, you could say that all the evidence until now proves that it doesn't interact with anything in a measurable way, besides brainwaves (which are just regular electrical activity in the nervous system) and whatever the body does (which is explained by nerve signals coming from the brain).

To believe that something exists, you make observations that your current theory can't explain and try to explain them. Here the root observation is that we "feel" conscious, we feel that we are something more than the physical objects that are our bodies. This is an observation about the state of our brains, it's not an observation about the rest of the world. It doesn't need any new laws of physics to be understood and it doesn't give us any data that we could use to build such a law. The only reason you're giving weight to this is that you are wired to see humans as something special. It's a reflection of the way you think. When you correct for that bias, there's nothing left.

It's much like believing that a god exists, built the universe, looks and thinks and feels like a human, and wants us to be good. It's so obviously something that humans naturally want to think because it matches with their inner biases that it's not worth considering as a scientific hypothesis. It's completely explained by the brain being wired to see humans (and living things in general) as something "special" because that helped with natural selection.