penny wise and pound foolish
Definition from Wiktionary, the free dictionary
From the British currency (one penny being 1/100th of a pound or, prior to decimalisation, 1/240th of a pound)
- (idiomatic) Prudent and thrifty with small amounts of money, but wasteful and profligate with large amounts.
1942, Harry Elmer Barnes, Society in Transition: Problems of a Changing Age, pages 122:
- In the past our government has nowhere been more penny wise and pound foolish than in connection with its expenditures for conservation.
thrifty with small amounts of money but wasteful with large amounts