Might help if you open your eyes a little. As for not being at risk in Gaul, are you serious? He was sometimes found in the front rank fighting alongside his men. I call that a little risky, never mind the hazards of war lasting for years, involving not only the defeat of an entire region but twice making a landing on foreign shores.
Caesar did not destroy the sovereignty of the Senate. They never had any to begin with. But as it happens, Caesar was careful enough to recognise that the Senate contained the most influential men in society and treated them respectfully even after assuming full ruling power as dictator-for-life. Hardly Rome's greatest enemy, and bear in mind, it was a minority of senators who acted against him, typical of their comnspiratorial behaviour.