Here's why:
* He falls for the stranger's elaborate story: Smiley readily believes the stranger's tale about betting on a frog's jumping abilities, even though it seems improbable and the stranger acts suspiciously.
* He trusts easily: Smiley is too trusting and doesn't question the stranger's intentions, even after noticing his suspicious behavior.
* He lacks critical thinking: He doesn't think through the potential consequences of his actions, and he's easily swayed by the promise of a bet.
Smiley's gullibility is what ultimately leads to his defeat, as the stranger tricks him into losing his beloved frog.
While Smiley is also known for being a gambler, his love for betting is a side effect of his gullibility. He readily believes in the possibility of winning, even when the odds are stacked against him.
Therefore, Smiley's greatest weakness is his gullibility, which makes him vulnerable to exploitation and ultimately leads to his downfall.