Shemeska said:There's always someone bigger.
If that's somebody to strive take down, fine. If that's a patron who genuinely needs your help, fine. If that's somebody to actually do all of the important adventuring while the PC's do mop-up work, kindly turn in your DM credentials at the door.
That's a somewhat hyperbolic way of putting it, but suffice to say, if you don't think PC's should ever be doing anything of significance, go ahead and make sure they know that up front so they'll decide for themselves if your campaign is a waste of their time.