FBI agent and white hat hacker aren't even in the same Venn diagram
As mentioned by other commenters, the FBI isn't exactly welcoming of people who typically live outside of normal law enforcement culture. Even if you're a "cybersecurity specialist", you're a Special Agent first. This means it's a law enforcement job predominantly, there's a huge gun culture, and the "bully police officer" mentality is strong. If you don't fit that mold you're not going to do well there.
To lawfully get a top secret clearance, you basically need to not use drugs ever, have very little outstanding debt, have absolutely nothing in your background that some overworked investigator won't find alarming, and never have had any run in of any kind with the police. There's a good reason for this; it's been shown that people with things to hide are easily converted into spies. But at the same time, it makes a lot of hacker types ineligible. In addition, the bureaucracy is an anathema to most people who would be desirable candidates. As a result, ex-military people gravitate towards jobs like this, but they aren't necessarily the best fit.