What is the difference between my brain calculating a response to the input it is receiving and a computer performing some calculation?

If there was a being that understood every process occurring within my brain he would be able to calculate what I’ll do before I do it. And it would be trivial to him.

Furthermore, the response my brain produces is purely a result of the input that is given to it. Similarly with a computer.

So why should I not assume that a computer has some subjective conscious experience?