Well the game is "Last of Us" not Last of me. Nothing selfish there. The chances of vaccine being a success on a large scale seemed almost zero.
Many others have said it better than me as to why the ending fit really well with the rest of the game. The part towards the end where he is running out of the firefly building is very similar to the starting where he carrying his daughter in the same manner. He has been through a lot and scars of not being able to save Sarah are still haunting him. Saving Ellie is his redemption. It is easy for us to sit on our comfortable chairs and say things like i would have done different or it was selfish. In reality things can be far more complicated.
My 5 cents.







