expression
extravagant; wasteful with money
Describes a person who spends money freely and carelessly, often beyond their means.
彼は金遣いの荒い人で、給料日前にはいつもお金がなくなる。
He is wasteful with money and always runs out before payday.
金遣いの荒い生活を改めないと、将来が心配だ。
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.