Fate Core p. 71
Finally, and this is very important: if a player wants to compel another character, it costs a fate point to propose the complication. The GM can always compel for free, and any player can propose a compel on his or her own character for free.
Say I'm a player. I notice an aspect that another player could compel, however, it seems I'm the only one who has noticed this possibility. I want to make the player and the GM aware of this, but I don't want to spend a fate point.
What's the purpose of this conflict of interest? What happens if a player suggests a compel and doesn't have any fate points left? Am I misunderstanding the rules?
EDIT: Oops, I read it as "compel another player" not as "compel another character" I don't know how I managed to mis-read it and mis-reread it several times.