It's hard to imagine why people would want to pay money just so they can be scared to death.
この場合、次のような言い方ができますよ。
ーIt's hard to imagine why people would want to pay money just so they can be scared to death.
「なんでお金を払って死ぬほど怖い思いをしたいのか理解できない」
It's hard to imagine ... で「考えられない・想像に苦しむ」
to be scared to death で「死ぬほど怖い思いをする」
ご参考まで!