I don't think of these people as predators but rather desperate to be able to accomplish something with few avenues available to achieve it.
Think of it this way:
A) you want to compete
B) your at a level where the pickings are very slim
C) you feel time is of the essence due to age, physical ability or both
D) you have tried out people or looked around with no success
E) another competition season is starting and you feel lthat once again you are going to be watching instead of participating
F) you think that if you don't find someone soon everyone will be taken
With all this in mind you now may find yourself facing three more options.
1) you see a couple that may be on shakey ground so do you do the right thing and wait and see what happens.
2) do you take the chance that someone else may be noticing the same thing but approaches the person before you and so snaps them up first because you hesitated.
3) or men do you do what most ladies do and and check with friends who know the couple rather than putting your neck on the lline, foot in your mouth and create bad feelings and be called a predator. Ladies do the checking underground and so the couple never know that their situation was being scoped out (nor does the ladies current partner if they have one they are thinking of trading in) and the world is still at peace. Another reason why women should rule the world.
Well anyway put yourself in this person's place and you may be surprised that all of a sudden you just may be desperate enough to become a Predator too.
(Just don't fight the Aliens and make another sequal though, okay).