He decided that saving it was more trouble than it was worth.

主语+谓语动词+that从句作宾语

that从句结构为动名词短语作主语，was more trouble than it was worth为系表结构（习语），不再继续分析。

翻译：他认定把钱存起来是不值得的。

划线部分为习语，be more trouble than it is worth 意为某事是不值得去做的。没有必要对习语再做语法分析（除非你自己会分析），记住这个习语的用法即可。