My math shows the technology to be 22 years old.
DC-X: First flight (and first successful propulsive landing) 18 August 1993
https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-X
"In December 2015, a Falcon 9 accomplished a propulsive vertical landing."
https://en.wikipedia.org/wiki/SpaceX
See also:
https://en.wikipedia.org/wiki/VTVL
Not mentioned in the above link was an amateur group developing VTVL tech around the San Francisco bay area in the 90's. IIRC, it was EPRS. FWIW, they also invented a multi-rotor platform to test their conrol system that evolved into the modern drone.