extravagant; wasteful with money
Describes a person who spends money freely and carelessly, often beyond their means.
He is wasteful with money and always runs out before payday.
If you don't change your extravagant lifestyle, I worry about your future.
A variant with が instead of の, slightly more colloquial and often used as a predicate.
A set phrase combining 金遣い (spending money) with 荒い (rough, wild). The expression is transparent and not historically obscure.