"Good guys do not finish last." refers to the belief that they have to WAIT until most women are done with their "bad boy" phase.
I believe most "good guys" are respectful of women maybe to the point of appearing as though they lack confidence themselves! Anytime a woman tells a guy "He's too nice" she's telling him that he is not a "challenge". His adulation of her bores her to death!
"Bad boys" make women (earn) their time and affection. Oftentimes the women are aware they have "competition" with other women. The "bad boy" never lets a woman know where she stands with him. His breaking promises makes him "unpredictable" and even "mysterious"
A lot of "good guys" sit on the sideline and don't receive any acknowledgement until these types of women experience enough heartache or become fed up with riding the love roller coaster.
They turn to the "good guy" to finally (settle) down with. He's not what she "really wants" but he is (good) for her. Author Lori Gottlieb wrote a book: "Marry Him: The Case for Settling for Mr. Good Enough"
I suspect there are some women who choose husbands for "practical reasons" while their heart beats for a "bad boy" in their past. Other women mature and can't believe how much crap they put up with!
All said and done the old adage used has a lot of validity for quite a few "good guys". They've never had women proactively pursue them.