fusion of Old English winnan "struggle for, work at, strive, fight," and gewinnan "to gain or succeed by struggling, to win," both from Proto-Germanic *wenwanan (cf. Old Saxon winnan, Old Norse vinna, Old Frisian winna, Dutch winnen "to gain, win," Danish vinde "to win," Old High German winnan "to strive, struggle, fight," German gewinnen "to gain, win," Gothic gawinnen "to suffer, toil"). Perhaps related to wish, or from PIE *van- "overcome, conquer." Related: Won; winning.
Sense of "to be victorious" is recorded from c.1300. Breadwinner preserves the sense of "toil" in Old English winnan. Phrase you can't win them all (1954) first attested in Raymond Chandler. Winningest is attested by 1804.