I was educated in Britain and didn't read it for school (but did read it during that time in my life) but I always took the point of it to be that the "American

I was educated in Britain and didn't read it for school (but did read it during that time in my life) but I always took the point of it to be that the "American Dream" wasn't ever real - it still mattered (at least in the 20s) where you were from, how you grew up and whether you were "old money" or "new money" and moreover the idea of the rags to riches story was in reality a fiction, in contradiction to the ideal Americans told/tell themselves about their country and society. This is, I think, why it's said by some to be an exemplar of "the Great American Novel" - a novel which says something meaningful about America as a country and society.