We are able to track down and physically explain (thanks to MRI) the sentation, the objective part of consciousness (Chalmers's 'easy problems of consciousness'). That really exist and we can prove it (or we have an idea about experiments to run to prove it)
I suppose here you're talking about the subjective sentation, the phenomenal experience, the 'hard problem', and you reference the 'cogito' not because you are a dualists, but because you truly think Descartes was right on this point (and this point only, the rest was extremely weak).
I will argue that you're wrong. There is absolutely no evidence to the cogito, at most billions of anecdata from homo sapiens who all have similar brains and reactions!
Some people believe subjective experience do not really exist [0][1]. A simple explanation would be: if we are somehow able to predict, by pure observation of predictable physical reactions, how an organism will act and react, including the fact that he will believe in a subjective experience, then we do not need to think subjective experience really exist. This is merely a tool for our bodies to create a sense of self unique through time, created from our own continuous perceptions, to allow our brains to strategize and avoid dangers.
[0]https://doi.org/10.1007/s11229-018-02071-y
[1]https://github.com/keithfrankish/articles/blob/master/Franki...