So, the person is better off dead.

那个人死了会更好。

You'd be better off, well, you'd be better off dead, right?

你最好还是死掉得了 不是吗？

There's a range - from passive suicidal ideation, where a person thinks they would be better off dead, to active suicidal ideation, where a person starts to make specific plans to die by suicide.

自杀意念是一个范围概念，从被动的自杀意念（思考这世界上没有他们会更加美好）到主动的自杀意念（谋划一个具体的自杀计划）。