It's not even a gamble really, his presence alone changed Leicester from an ailing pub team to English champions. We have to remember that players like Vardy and Mahrez were already there when the team was one of the worst in the PL. When they signed Kante in 2015 the whole teams mentality suddenly changed. He was not part of a miracle, he pretty much made it happen, and made mediocre players like Drinkwater look so much better alongside him. Plus he's 25 so he has plenty of years ahead, and has resale value if he suddenly starts to suck. For 25mil it's a no brainer really.