In the modern era, wars are rarely in the interest of either side. However, miscalculations happen, and the more you play at the edge of war, the more likely you are to fall over.
In April, Israel calculated that they could bomb an Iranian complex in Syria, targeting top Iranian officials without sparking a war. They were correct.
In response, Iran calculated that they could send 300 drones/missiles to Israel, and have enough be intercepted by air defense systems to avoid starting a war. They were correct.
Israel and Hezbollah have been exchanging fire; each side calculating that each strike would not start a war. Thus far they have been correct.
For years, Hamas and Israel have been exchaning small attacks. Both sides correctly calculating that they could avoid a full war. Then, on October 7th, the IDF fucked up. A Hamas attack was far more successful than it had any bussiness being, and now both sides are 10 months into a war that hurts both of them.
A war with Hezbollah might not be inevitable, but the current level of conflict is not sustainable. Every day that it is not resolved is one more opportunity for miscalculation; and one more notch ticked on the escalatory ratchet.