be penny-wise and pound-foolish

Penny wise and pound foolish描述的是一种集中精力在小事情上节省小钱，而错过了节省或获得大量金钱的机会。Penny(便士)是pound(镑)的辅币中的最小币值。

举个某人是 penny wise and pound foolish的例子，一个人为了买打折的商品，跑了很多杂货店，但最后花的路费比他在杂货店买打折商品时省下来的钱还多。另一个being penny wise and pound foolish 的例子是，某个人用劣质的瓦盖房子，结果因为屋顶漏水而造成昂贵的维修费用的损失。这种情况下这个短语的意思就跟中文中的“因小失大”是一致的。

I know you don't want to pay for this expensive course of treatment, but when ignoring your health lands you in the hospital, you'll see that you were penny-wise and pound-foolish.

我知道你不想为这个昂贵的疗程买单，但是当你因为忽视你的健康而进了医院，你就会明白你是因小失大了。