Isn't it stupid, the mankind seeking immortality?

To add since it hasn't been said, life just kinda sucks overall, why would anyone want to live forever?

"Stupid" is nothing more than dismissive and inarticulate insult. If you could put into words, why you think it's stupid, I could tell you whether I agree with you or not. I can think of pros and cons to seeking immortality. 

It is not stupid to want to breathe, to move, to live forever. No one but the very ill or depressed want to die. If we are content to die, it is because we believe that we - our souls or inward being - will become even more alive and free outside or wretched bodies.

We don't want to stop being aware. We don't want to stop existing. We don't want to be forgotten.

The stupidity is that we think we will get what we want.

It is stupid, because it’s vanity and impossible.  Everything dies in the end.

I do not think mankind as a whole is seeking immortality. Perpetuating the species is not the same as immortality, which is impossible because the the sun and our solar system, and the universe itself will not last for ever. I think most people are aware of this scientific fact.