You're too fast. If you can free your mind, the body will follow. Between you and me, if Morpheus says you can fly, I wouldn't go jumping out any windows to find out if he's right. You know, I know that this steak doesn't exist. I know when I put it in my mouth, the Matrix is telling my brain that it is juicy and delicious.
Ignorance is bliss.
They're sentient programs. They can commandeer any software hardwired to the mainframe. Anyone that is still in a power plant. That is why we try to be invisible in the Matrix. The best hacking is always traceless.