When a person is struggling, the last thing I want to tell them is "It gets better". No. That's not what they need to hear. That's empty hope that won't accomplish anything.
The truth is this: For every case of a person that managed to improve their bad life circumstance, there are many more that never got that chance. Survivorship bias makes many believe that "it gets better", but this is objectively untrue. You do not ever hear of the ones that it did not get better for, because they are dead. You only hear about the success stories.
Worse yet, this seems to be a motto for suicide counselling and emotional support in general. It's a hope-based slogan, but it is an incredibly flawed one.
This is not to say that one should always be pessimistic and rule out any possible chance of improvement. Being realistic is important. Either way, it is a gullible thing to say, on top of being statistically and existentially flawed.
A way better approach for emotionally comforting a person in crisis is to acknowledge their suffering and let them talk to you. Understand them, and show them affection. Put in work to actively care for them and insert yourself into their life to be a pillar of actionable support instead of just saying "I'm sorry" and "It gets better".