So buying one ticket is "infinitely" better than buying no tickets.
You're looking at the (potential) benefits and ignoring the costs. The costs are not negligible: "Thirteen percent of US citizens play the lottery every week. The average household spends around $540 annually on lotteries and poor households spend considerably more than the average." (source).
Buying more than one ticket, comparably, doesn't make a difference.
Buying a second ticket doubles your chances, obviously.
A LessWrong reader buys a lottery ticket ... in at least one worldline, somewhere, they win a half a billion dollars
For each timeline where you buy a lottery ticket there is one where you don't. Under MWI you don't make any choices -- you choose everything, always.
the marginal utility of one extra dollar is basically zero
You've never been poor, have you? :-/
It is trivial to show that buying a lottery ticket is rational in this scenario
It is just as trivial to show that you should spend all your disposable income and maybe more on lottery tickets in this scenario.
You're looking at the (potential) benefits and ignoring the costs. The costs are not negligible: "Thirteen percent of US citizens play the lottery every week. The average household spends around $540 annually on lotteries and poor households spend considerably more than the average." (source).
I'm only commenting to the rationality of one individual buying one ticket, not the ethics of the existence of lotteries.
Buying a second ticket doubles your chances, obviously.
Buying one ticket takes you from zero to one, buying two tickets takes you ...
As per a recent comment this thread is meant to voice contrarian opinions, that is anything this community tends not to agree with. Thus I ask you to post your contrarian views and upvote anything you do not agree with based on personal beliefs. Spam and trolling still needs to be downvoted.