I don't think most people would say that Djokovic "isn't popular," which is something you've said...
I don't know what most people think. I've stated "it's been said many times that Djokovic lacks popularity compared to Federer and Nadal.". See this link http://ftw.usatoday.com/2015/09/no-one-likes-novak-djokovic-us-open-win-roger-federer
My point about "facts of life" was that Nadal (and Federer) already had huge fan bases when Novak wasn't really in the conversation. Since both are still playing, and given that their fan bases are somewhere between pretty loyal to ridiculously biased, I'm saying that that has left not a great lot of tennis fans for Djokovic to sway into his fan base. You get that, right? However, new tennis fans are made all the time, and certainly that would contribute to the Nole fan base.
You clearly said it's a fact that Federer and Nadal are popular than Djokovic and you still haven't proved it.
As to your other questions: I have no idea how much the majority of crowds in the USA support Djokovic. My question to you would be: compared to whom?
Compared to Fedal.
However, I think my argument is compelling for why Rafa is likely more popular in Latin America than Novak, and, frankly, Roger.
There is a big difference between making a compelling argument that something is "likely" true and "definitely" true. Anyway, this thread isn't about who has more fans but whether Djokovic, relatively speaking, isn't popular.
so you got to admit that Djoker does get the credit he deserves, or even more.
I don't think Djokovic gets credit he deserves in the USA, Western Europe etc.