Mammonism is the greedy pursuit of material riches: chasing money and wealth above all else.
The word mammon comes from the Hebrew word for "money," and it is famously used in the Bible in a quote usually translated as "You cannot serve both God and mammon." Over time, literary traditions personified Mammon as a demon of avarice who tempted people through greed. But mammonism doesn't usually mean the literal act of worshipping this hypothetical demon; instead, it just means an obsession with material gain and the accumulation of riches.