I would agree if it were a female lion. As it's a male, he was likely hunting solo and bit off more than he could chew.
"Pride before a fall", or some lame pun like that.
What TeenerTot said. Male lions with prides restrict their activities to fucking lionesses, killing hyenas (and their predecessor's cubs), marking territory, keeping out other males and STEALING kills, not making them.
On the contrary there are male lions that make up prides consisting only of other solitary males known as nomads, but usually they are related by blood. They do hunt together similar in a fashion to females, but this lion appears to be a bachelor.
A more experienced cat would have stopped to lick its crotch before sauntering off casually, to emphasize that it didn't really want to catch that buffalo anyways.