I actually don't think there anything anyone can say that can even get close to making me as angry as I am when I hear this from people "helping". By all definitions of the word, that sentence is an absolute lie. You don't know that any better than I do, in fact, if it's coming from a complete stranger, I'd say you know even less. It's ignorant, pretentious and almost insulting.
Worst part is that it can be way less harmful with just a simple change. Just replace "going to" with "can". Unless you're talking to a child, the difference is very obvious. Why pretend that you know everything and the person who's already struggling is just too stupid to see the "right" thing? At the very least you're not lying now. It's true, the possibility for things to change is there, even if the probability itself can vary, factually it is true. This way you're actually giving hope instead of just being arrogant. Why is that so difficult for so many people? How hard is it to change a single word? It's absolutely infuriating.
Ironically though, I wonder just how many times this single phrase actually pushed someone over the edge, probably a significant number.