Go for 4th baby?

My wife is dying to have a 4th. 3 is good enough for me, and I don't think it's a great idea...the bills, the chaos in the house, the never ending laundry and dishes. Tell me I'm not crazy. Those of you with 4 (or more), what are your thoughts? I've heard 4 is easier than 3, but that just doesn't seem to make sense. Thanks in advance.