Martial Arts Hook Kick ( Kung Fu)?

I remember when I was younger I watched a guy was a known TKD guy do a combo roundhouse/hook kick (consecutively) on some gangster wannabe as his first attack. The gangster wannabe took the full force of it and was quickly defeated. So anyone that says that high kicks or hook kicks don't work have never used them or trained to use them in real life. I know from my own experience that I have done a jump side kick right into a guy's chest as a first attack (that was when I was younger and in better shape) as a first attack and I nearly knocked him on his .