When a person eats and drinks [as part of celebrating a holiday], they are obligated to feed "the stranger, the orphan, and the widow" (Deuteronomy 16:11).

But someone who locks the doors of their house, eating and drinking with their children and spouse [alone], and doesn't provide food or drink to the poor and depressed, is not participating in the joy of [God's] commandments but rather the joy of the gut, and about them it says, "their sacrifices are like bread for the dead; all who eat of them will become impure, for their bread is for themselves" (Hosea 9:4) Joy like this is disgrace for them, as it says, "I will strew dung upon your faces, the dung of your festal sacrifices"(Malachi 2:3).

haggadah Section: Maggid - Beginning
Source: RAMBAM, MISHNEH TORAH, LAWS OF YOM TOV 6:18 [translation by Mechon Hadar]