character motivation - Why did Vizzini want to start a war?

In The Princess Bride, there are at least two different people who aim to start a war between Florin and Guilder by assassinating the princess: Vizzini and Prince Humperdinck.

Now rulers seeking excuses to start wars with neighbouring countries is a common enough phenomenon: perhaps Humperdinck is ambitious and wishes to conquer Guilder, but needs the support of his people before he can declare war upon them. But what about Vizzini? What interest does a Sicilian have in starting a war between these two countries, and why does he take so many risks and expend so much effort in order to do so?

What was Vizzini's motive for starting a war between Florin and Guilder?

_{(This question was inspired by our Princess Bride movie night last night in Mos Eisley.)}

Answer

Because Humperdinck hired him to.

He mentions it when he and Count Rugen are outside the Pit of despair. The first plan was for Vizzini to kill her near Guilder to spark a war. Plan B is for Humperdinck to do it himself.

I know, the people are quite taken with her. It's odd, but when I hired Vizzini to have her murdered on our engagement day, I thought that was clever. But it's going to be so much more moving when I strangle her on our wedding night. Once Guilder is blamed, the nation will truly be outraged - they'll demand we go to war.

It's notable (since @Geoff notes it in comments) that Vizzini also thinks he's part of a grand undertaking.

I've hired you to help me start a war. It's a prestigious line of work, with a long and glorious tradition.

Since we're not really given anything else about his history though, we don't know how many other wars are on his resume, so it's also very possible he just likes inflating his ego and being part of Humperdinck's plan makes that easy.