What does this saying even mean?

Why do you think of the saying below:

"If the girls go with and love the bad boys, the losers in the end are not the bad boys or the good boys but the girls themselves."

What does this saying mean? I tried asking some individuals why they believe this saying but they're only answer to me is that in the end, good males are not the same people they once were or in the end, they are mentally focused somewhere else.

So what does this saying mean?
What does this saying even mean?
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