Stronger word for "selfish"

Solution 1:

Synonyms like "egoistic", "egocentric", "self-centered" "self-loving", etc, are no stronger than selfish. I would use an adverb before "selfish" lest its exact meaning be changed. "Egocentric" and "self-centered" are not exactly the same as selfish.

He is extremely/incredibly/profoundly/exceptionally/monstrously/etc selfish.

Solution 2:

Egomaniacal:

overly concerned with one's own desires, needs, or interests

a brilliant but egomaniacal urban planner who ruthlessly sought to impose his vision of the ideal cityscape (M-W)

Solution 3:

Avaricious denotes a kind of selfishness that knows no limits.

From the link:

avaricious | adjective | av·a·ri·cious | \ˌa-və-ˈri-shəs\

greedy of gain; excessively acquisitive especially in seeking to hoard riches

an avaricious scheme to con the elderly couple out of thousands of dollars

Solution 4:

I respectfully disagree that an adverb is the ideal route. English is the richest lexicon that has ever existed: you have an arsenal of words from which to choose the ideal way to fillet your subject.

Your question is short, but you asked for a word that conveys two meanings: selfishness, and that the selfishness is "wrong." I will interpret that as morally wrong.

We say people are inconsiderate when they are selfish in a situation when it is wrong to be selfish.
Self-seeking and self-serving both connote selfishness that is wrong.
In specific situations, such as the case of the cookie caper, narrower words are fantastic: gluttonous and greedy are so wrong that Christians list them as two of the seven worst sins.
Stingy and parsimonious are clearly wrong, but the selfish aspect is not as strongly present as some of the other words.