Downvoted for (1) being an extraordinarily laborious way of saying "decaying exponential times modest-degree polynomial is rapidly decaying", (2) only doing the laborious calculations and not mentioning why the result was pretty obvious from the outset, (3) purporting to list ways around the problem (if it is one) and not so much as mentioning "don't discount exponentially", (4) conflating "rationalist" with "exponentially discounting expected-utility maximizer", and most of all (5) the horrible, horrible I-know-I'm-going-to-be-downvoted-for-this-and-you're-all-so-stupid sympathy-fishing.

[EDITED to fix a typo: I'd numbered my points 1,2,3,5,5. Oops.]