Can we ever get them for our own usage?
It's possible to buy ex-Soviet fighters like the MiG21, and there are a few older Korean War era US jets like the F-86 in civilian ownership. The US used to sell old fighters as surplus after they were demilitarized, which meant the weapons capability removed. They changed the definition of "demilitarized' in the late 50's, so surplus planes had to be cut into pieces and sold as scrap. Newer military aircraft on display at aviation museums are legally "on loan" from the military and cannot be sold. So no, as a general rule you cannot buy a U.S. or western European fighter built in the last 50 years. There was one example of an F104 in civilian hands, but it was pieced together from chunks of six or seven different planes. There have been a few types that were widely exported, like the F-5, that have been at least advertised for sale, but they are very rare.
There are a pair of MiG-29's in private possession, though I can't remember exactly where. Somewhere in the Central U.S., I think. There are MiG-15 and MiG-17 owners as well. I think the U.S. quit allowing its used warbirds to fall into public hands to skirt any potential liability issues. . .
Far cheaper to own a gold-plated Rolls Royce than to fly an ex-military liability. even if you could afford to get a pilots licence you could never afford the fuel and maintenance costs. Pray, do tell which imaginary star who owns an ex-military jet?
It's possible, but expensive. The aircraft will have to be de-militarized, of course. I know that there used to be a guy in Burlington, VT who owned a MiG-21 in mid 1990s. He kept it at Burlington Airport and flew it in air shows. The University of Vermont is near the Burlington Airport. In April 1996 I was taking an exam for my Professional Engineer License on campus, while the guy was doing very loud touch and gos in his MiG. I don't know if that guy still owns the MiG-21 or if it is still flyable now. There are also some L-29 Delfin and L-39 Albatros jets in private hands in the US. These planes were used as advanced trainers by the Warsaw Pact countries during the Cold War. Some are still in use in that role. Michael A. Chowdry, founder and president of US cargo airline Atlas Air died in a crash of his personal L-39 in January 2001. There are also some western built former military aircraft in private hands. A privately owned ex-Royal Navy Harrier took part in the air show at Dover Air Force Base in August 2017, for example. A private World Heritage Aviation Museum owned a deHavilland Venom license-built in Switzerland but it crashed last July. Some private companies also own some retired Hawker Hunters and A-4s. These are used for weapons and radar testing and military training support under contracts to the US Department of Defense. There is also a flying private CF-104 in Norway. Getting your hands on an F-4 or an F-5, however, is not possible. Iranian Air Force still flies these models and the F-14 it obtained before the revolution. After Iran got some illegally smuggled parts from the F-14s being scrapped by the US Navy, the US government made sure that none of the F-4s, F-5, and F-14 or their parts make it to private owners.
This guy on YouTube did it. He posted his story here: https://youtu.be/-PHcdn8R4d4
0NE TRlCK P0NY
I've seen privately owned F85s, F5s and an F104 Starfighter. The FAA and USA armed forces are reluctant to let civilians have supersonic surplus fighters but a few creative individuals have managed it.
Assuming the "THEM" you're asking about are small private airplanes, people have been buying them for their own personal use for more than 100 years. All you need is a pilot's license and enough money to buy and maintain an airplane.
No, you couldn't afford it anyway. Name a celebrity that owns one.
The only thing an ex-military jet is allowed to be used for is airshow work. They are not and cannot be used for personal transportation.