avaricious
Having an extreme, never-satisfied greed for money or things.
Avaricious means having an extreme, insatiable greed for wealth or possessions. An avaricious person wants more and more money or things, never feeling satisfied no matter how much they already have.
Think of the difference between wanting to earn money and being consumed by greed. An avaricious banker might already be wealthy but still treat clients unfairly to accumulate even more. An avaricious landlord might own dozens of properties but still try to squeeze every possible penny from tenants. The word describes someone whose desire for wealth has become excessive and unhealthy.
You might recognize this trait in literature: Ebenezer Scrooge from A Christmas Carol starts out deeply avaricious, hoarding his money and refusing to share even during the holidays. Dragons in fantasy stories are often portrayed as avaricious creatures, jealously guarding massive piles of treasure they'll never use.
While ambition and wanting to succeed are normal, avarice (the noun form) describes greed that has become excessive, where accumulating wealth becomes more important than relationships or kindness.