have seen 3 of my schools continue with students who stated at the outset that they wanted nothing but commercial who were undoubtedly going to have to pay well over the odds.
In which case, that is what you tell them. But... "Fred, you seem to be struggling a bit, and it's going to take you well over minimum hours and cost you a lot of money to do this", is very, very different from..."Fred, you're never ever going to make it as a pilot, no matter how hard you try".