Question 1151738
The probability of winning is 1/99999 and that payoff is (500-1)/99999 or 0.00499
The probability of losing is 99998/99999 and that loss is that fraction or -0.99999 which really rounds to 1.00
so the expected value is - 1-0.00499 or -$0.99501 or -$0.995.
Note that I am not using 0 here.