Single word for someone who socializes in excess [duplicate]

They are known as "trust-fund babies" or "trust-fund kids":

from Dictionary.com:

noun: a child of wealthy parents or other relatives who can rely on a trust fund rather than hard work for a living

Traditionally the most common (noun) terms for such a one would probably be a "prodigal" (as in the proverbial, Prodigal Son) or, alternately, a "profligate".

prodigal noun:

1. a person who spends money in a recklessly extravagant way.

• a person who leaves home and behaves recklessly, but later makes a repentant return.

noun: prodigal son

synonyms: wasteful, extravagant, spendthrift, profligate, improvident, imprudent; see Google prodigal

profligate noun:

1. a licentious, dissolute person. "he was an out-and-out profligate"

synonyms: libertine, debauchee, degenerate, dissolute, roué, rake, sybarite, voluptuary

see Google profligate