I don't agree that "it doesn't get better".

Better isn't a perfect utopian state that you reach and you stay in.

Rather, it's any other state than "suicidal despair" that the suicidal person is currently feeling.

I have had multiple people I love go through suicidal periods.

One was my partner, who was suicidal for 18 months after he accidentally killed someone while delirious on magic mushrooms. He was in prison, wracked with guilt, realising he'd destroyed someone's life, someone he loved, and also ruined the plans he and I had had for a life together. I did tell him "it will get better". And it did. He's still in prison. He still killed someone. But he now is able to live a meaningful life, to experience love and happiness and do good things with his life. He's no longer feeling the black pit of despair that he was feeling when he was suicidal. So it DID get better.

The second person I love who was suicidal is my best friend who has OCD. Frequently his intrusive thoughts make him feel like he doesn't deserve to live. I have told him "it gets better" because when he's suicidal he forgets that when he's not in these periods, he feels happy, he enjoys life, and he's always grateful he chose life. Even though his mental illness throws a shroud over his happy memories and makes him doubt that he can be really happy ever again, I tell him "it gets better" and he trusts me, because I'm his best friend. And it DOES get better. Not permanently. But the periods in between his OCD attacks, he IS happy. He has love. He has hobbies he enjoys. He has spirituality. He has fandoms. He has a boyfriend. He has a job he enjoys, and countless friends who love him.

So yes, it does get better. But better isn't a permanent state. Better isn't saying you will never feel bad ever again. It's saying that the feeling of suicidal despair will not last forever, and that there are alternatives to killing yourself than "suffer relentlessly forever".