The Bulgarian student who got MI-17s is an Aviation Leadership Program student. The USAF asks and pays for countries to send students for pilot training. The ALP students go through an extended T-6 phase, but no advanced phase. It wasn't a waste for Bulgaria because it cost nothing to get a USAF trained product. See further: https://static.e-publishing.af.mil/production/1/af_a3_5/publication/afi16-108/afi16-108.pdf