Hezbollah won against Israel since Israel withdrew from southern Lebanon.
The primary reason why Hezbollah won is that Israel underestimated Hezbollah capabilities so idiotically much!
Missile and rocket strategy
Hezbollah rocket and missile firing strategy also really surprises Israel. Israel felt helpless against those Hezbollah rockets, especially when they successfully hit the train station in Haifa. Israel could not continue having its main cities being in that level of horror ( as this would threaten its existence)
Competency of Hezbollah fighters
Hezbollah fighters were so well trained that even the most elite units of Golani and Paratroopers Brigade could not dominate them. In the last days of July, if I’m not wrong, IDF was deploying their best ground forces but not only that they all failed, Hezbollah did not seem to be seriously hurt as the result. This was an awful psychological defeat for the IDF officers. The techniques that Hezbollah fighters used were so well thought and planned, a class of its own and the best asymmetric warfare that could challenge any army in the world. The anti-tank missile that Hezbollah used also proven to be extremely effective against IDF Merkava tanks, while IDF thought Merkava tanks are almost invisible and impossible to be defeated.
Israel, perhaps, had forgotten who is behind Hezbollah!