You can fight and lose but if you do nothing, you've…

“If you fight you might lose, if you don’t you have already lost.”

Bertolt Brecht (1898–1956) German poet, playwright, theatre director

Disputed

“There are four things that make a man fight as you just did," the duke explained to Rumbold. "Love, despair, anger, or insanity."

Erik counted them off on his fingers. "Everything to lose, nothing to lose, someone's taken it, or you've lost it.”

Alethea Kontis (1976) American writer

Source: Enchanted

“Because if you don't stand up for the stuff you don't like, when they come for the stuff you do like, you've already lost.”

Neil Gaiman (1960) English fantasy writer

Neil Gaiman's Journal (01 December 2008)

“But sometimes you lose. Nothing you can do but admit it.
-Eli”

Sarah Dessen book Along for the Ride

Source: Along for the Ride

“When you ain't got nothing, you got nothing to lose.
You're invisible now. You've got no secrets to conceal.”

Bob Dylan (1941) American singer-songwriter, musician, author, and artist

Song lyrics, Highway 61 Revisited (1965), Like a Rolling Stone
Source: da Like a Rolling Stone, n.° 1
Context: Go to him now, he calls you, you can't refuse. When you ain't got nothing, you got nothing to lose. You're invisible now. You've got no secrets to conceal.