That wasn't really a slap, that looked playful, it's meaningless, like an uncle's prank. Don't know anything about the guy, but he just looks angry the entire video, not sure if people are overreacting here. Doesn't seem like it was out of actual pure ego or something, is a little hard to tell if you don't know the people involved
Slapping people is manbaby behaviour. Particularly if it's slapping people who are weaker. A real man doesn't need to use his hands to earn respect. This was petulant and insecure behaviour in public and Turkiye loses face on the world stage as a result.
The little kid showed more emotional maturity and self control than a fully grown adult here.
I don't think it's abhorrent, I think it's weak. How is he so insecure that he reacts this badly to a little kid? The kid responded rationally, the president responded like a toddler.
Kids should learn not to just slap someone if they don't get their way. Adults are supposed to be more in control of their emotions than that. It looks weak and insecure.