A person who wastes money (or time) — a spendthrift; someone given to extravagant spending.
彼は浪費家で、給料が入るとすぐに高価な服を買ってしまう。
He's a spendthrift; as soon as his paycheck comes in he buys expensive clothes.
あの親戚は浪費家だと聞いているので、お金の話は避けたほうがいい。
I've heard that relative is a spendthrift, so it's better to avoid talking about money.
無駄遣いが多いと周りから浪費家だと思われることがある。
If you waste a lot, people around you may think you're a spendthrift.