Probably working in a foreign country protecting company officials of the largest American owned companies. Very hazardous job in any foreign country.
there is no single highest paying job, each one is paid on the skills of the employee and what the employer is willing to pay at the time, for instance if you are trained in firewall security and you find a company that needs a new firewall quickly you could get a nice gig at whatever you want to charge. But if you are ONLY trained in one thing then you are not going to be in high demand once the job is done, best thing to do is get a good grounding in all aspects of security a job like system admin who have to know about all sorts, then once you have a good paying job you can figure out the companies needs and specalise.
The Highest Paying IT security jobs would probably be working for the Intelligence Community.
You would then have to decide how much blood on your hands you would be able to live with in the name of earning money, because these are very shady organisations that have no real public over site at all.
Or Consider this:
Whether defending the US Constitution (or your equivalent) against all enemies,
foreign or domestic, requires you to follow Snowden's example.
if i had to guess i would say secret service or private security companies