Antonio Conte is betting on himself. He's betting that he can restore star-crossed players to greatness (or, at least, a level of output equal to their salaries/transfer fees). Betting that he can jolt Tottenham Hotspur to life. Betting that his "intensity/winning mentality schtick" -- which has generally been around as long as coaches, in any sport, have existed, but which he takes to another level -- will be so successful that it persuades the club to loosen the budget constraints and invest meaningfully in the squad.
(And -- a corollary to that last wager -- betting that if they don't spend, he'll still achieve enough that he'll be able to jump ship to a bigger club, hence his 18-month contract.