If a race lived long enough it would learn everything there is to know. We'll all shut up before long.
Dead beings are all pretty quiet.
The bad thing about dying, is that you leave someone grieving. The future depicted in a good SF story ought to be in fact possible, or at least plausable. In fact, it is the only such literature we have. When it has given up hope. By means of the easy and the simple we grasp the laws of the whole world.