The other day I was musing about a reasonable approach to playing games like the big lotteries. They don't cost a lot and losing $40 is not a life changing event for me, but clearly winning a few hundred million dollars is life changing.
My first thought turned to, well if you just play when the expected value is greater than the cost of the ticket that is "rational". But when I started thinking about it, and even doing some calculations for when that EV condition exists (for things like Mega Millions the jackpot has to be greater then about 550 million) it struck me that the naive EV calculation must be missing something. The odds of actually winning the jackpot are really, really low (as opposed to just really low to rather low for the other prizes). And the payoffs that go into the EV calculation are hugely skewed by the top prices.
I suspect this must be a situation that generalized to other settings and am wondering if anyone knows of better approaches than merely the naive EV calculation. And to be sure I'm using the term as everyone expects, EV just equals the probability weighted payoffs minus the cost of the ticket.
I agree that both DMV/DMU of money units is true and worth considering. However, I think it might be a bit more complex than that since I think one can make a case for network effects/economies of scale type aspects.
For example, the marginal value of the next dollar I add to my wealth today is pretty small. Clearly if I had 300 million additional dollars the MV of the next dollar absolutely will be smaller. But the MV/MU of having 50 million to put into my "this pays for my day to day life" and this other 100 million goes into some research projects I would like to see done but in no way could pursue that effectively now, and this other 100 million can go to some other useful (in my assessment) efforts that I might want to support and the remaining could be "wasted" on gifts and assistance to those I think deserve more than life has given them. So I think understanding just what the margin is matter a lot in this type of view.