Because “Greatest” is inherently relative. You can talk numbers and metrics derived from studies of attributes of different countries, but the word “great” is completely meaningless. And by the way… There aren’t too many metrics the US scores “great” on. We have a lot to improve as a nation, and it doesn’t help to call it the “greatest in the world” or say we could “make it great again.”
…and why is this Millenial nonsense…?