Who said "I've been alone. I know what it costs."?

This quote is attributed to Arrow.

I've been alone. I know what it costs. - Arrow

"I've been alone. I know what it costs."

Arrow Solitude

"My name is Oliver Queen. After five years in hell, I have come home with only one goal: to save my city."

"I'm not the man I was."

"You have failed this city."

"I'm a monster."

"Sometimes being the best means being the loneliest."

"Solitude gives us time to reflect on what matters"

"I'm not good with people, never have been."

"I feel like I'm disappearing."