Life is a series of ups and downs. Not everyone who experiences adversity is a loser.
That’s all good and well, but it doesn’t change the fact that the big three all fell from their pedestals in a major way and a big part of that failure was caused by their own actions. They were obviously the winners at the end of the OT, and through circumstances and their own mistakes let it all slip through their fingers. They lost almost everything they fought for over the course of a trilogy. I think the loser description is quite apt.