... most of them are dead.
You've never been to Bavaria, have you?
I guess in Saxony they have bigger problems with those people.
Three things come to my mind:
First, if your game awards some score or something then getting a hint must cost them.
And/or you only give a set amount of hints throughout their session. Maybe allow for an additional hint every x levels.
And/or make them aware that they have not succeeded themselves. I remember a good Solitair back in the MS-DOS days which also gave you a hint if you asked it to. When the game was finished it displayed ''You won (with my help)''. The ''with my help'' was what encouraged me not to press the button.
How many NASA managers does it take to screw in a lightbulb? "That's a known problem... don't worry about it."