It's not that simple. Owning a fighter jet (or even trainer like an Aero L-39) requires both the nod from the ATF, and a bunch of FAA waivers. For a high end jet like an F/A-18 or F-16, It practically requires the Secretary of Defense himself to approve it. Without that approval, Boeing or Lockheed Martin can't provide parts and support for the aircraft.
Notably, Erik Prince of Blackwater/Academi notoriety played fast and loose with weapons import/export/ownership rules, and came very close to being criminally prosecuted for it. Retired Admiral William 'Fox' Fallon resigned in disgust when he realized how far outside the rules Erik Prince was operating.
When Erik Prince suggested letting his private firm handle security in Afghanistan as an outsourced contractor, then SecDef (General) Jim Mattis was dead against it, and blocked it all the way.
Notably, Erik Prince of Blackwater/Academi notoriety played fast and loose with weapons import/export/ownership rules, and came very close to being criminally prosecuted for it. Retired Admiral William 'Fox' Fallon resigned in disgust when he realized how far outside the rules Erik Prince was operating.
When Erik Prince suggested letting his private firm handle security in Afghanistan as an outsourced contractor, then SecDef (General) Jim Mattis was dead against it, and blocked it all the way.