Why is USA starting world war 3 now?

It's not "USA", it's Trump. No debate in Senate, no declaration of war, no House vote. You need to reset your assumptions.

Epstein files?

I mean, just look at America's main ally and take a guess. Israel's political goals would be jeopardized by a complete release of the Epstein files. War with Iran fills a joint US/Israeli political initiative of taking the heat off politicians and creating a common enemy.

Why wouldn't Trump start WWIII now?

Effectively, it's a continuation of the Gaza and Ukraine wars.

Israel and Iran have been fighting for years, with Iran generally using various intermediaries. The October 7 attacks were orchestrated and funded by Iran.

Having spent several years punishing the Gazans for it, Israel is moving on to Iran itself. It has enlisted the help of the US, who are going along with it for a variety of reasons.

One of those reasons is Ukraine. Iran has been helping arm Russia, and evade sanctions. The Ukraine war has been called "World War III" for four years now, pitting the West against a coalition of opposing forces, of which Iran has long been one.

This is the best I can do to "sanewash" it. In fact, a good chunk of it is arrogance, stupidity, warmongering, and distraction.