Why didn't the man in the book Two Thanksgiving Day Gentlemen eat for 3 days?

It's hard to determine for sure from the story, but I think the idea was that it was because he was poor. He didn't have enough money to feed the homeless man a Thanksgiving meal, so to save up he went without food himself for several days, so he could provide him a true feast. Both of the men wanted to participate in the ritual, and it made both of them feel good... but this time they also both suffered for it, because that interaction they had once a year was very important to both of them... trying to make the other person happy. I think for each of them the suffering was worth the happiness that they believed they had brought about... but if they had both known the truth and been friends more than once a year, there probably would have been a happier outcome. :)