Making a very large profit; earning a killing (often used colloquially about business or investments).
新しい株の投資で彼は大儲けした。
He made a killing on the new stock investment.
祭りの屋台で大儲けすることもある。
Sometimes people make big profits running stalls at festivals.
彼はうまい商売で大儲けを狙っている。
He's aiming to make a big profit with a clever business plan.