Bait & switch, though.

“All it takes is for one to work out.” is not the same as "You just need the one [job] that’s the right fit." or "You just need the one [house] that feels like home." or "You just need the one [life partner]."

Author's examples are, spiritually, the opposite of their friend's advice - in fact, "all it takes is for one to work out" is something often said to people who lost hope because they got lost being too picky.

Simplifications always leave something out. It's like the three body problem: people think one factor matters most, and one other factor controls it. But once they realize there is a third factor that alters one or the first two, or mediates between them, it gets more complicated.