penny wise and pound foolish
Describes someone who is careful with small gains but wastes large amounts; literally 'picking up with fingernails and spilling with a winnowing basket'.
He fusses over small savings but wastes money on big purchases. Truly penny wise and pound foolish.
A Japanese proverb combining 爪 (fingernail) and 箕 (winnowing basket) to contrast meticulous small-scale effort with careless large-scale loss.