Why I think that the MWI is belief in belief: buy a lottery ticket, suicide if you lose (a version of the quantum suicide/immortality setup), thus creating an outcome pump for the subset of the branches where you survive (the only one that matters). Thus, if you subscribe to the MWI, this is one of the most rational ways to make money. So, if you need money and don't follow this strategy, you are either irrational or don't really believe what you say you do (most likely both).

(I'm not claiming that this is a novel idea, just bringing it up for discussion.)

Possible cop-out: "Oh, but my family will be so unhappy in all those other branches where I die." LCPW: say, no one really cares about you all that much, would you do it?