Verily I say unto you...

Because, honestly, a proven franchise, character or idea will reap the studio millions (possibly billions). Take "Superman Returns" for instance. With a confirmed budget of $260 million dollars, you'd probably think " what the hell was Warner Brothers thinking?" $260 million is nothing to sneeze at, and I'm sure it caused undo stress for lots of WB higher ups. And when domestic box office came in at $200 million...I'm sure you'd deduce WB panicked like a mofo. But this is where the all important foreign box office comes in, and with another $190 million dollars overseas, "Superman Returns" got the mother of all reprieves. I'm not sure even WB knew it'd take in this kind of money worldwide...they were counting on the domestic take to save the day.

I consider this to be a huge goof by a major studio that just happened to work out in the end...a rather large profit (but not what the studio expected) guarantees both a sequel, and the capital to pay for said sequel (and hopefully reap a higher profit as Bryan Singer delivers a more action packed flick).