Keep rereading the post you quoted until you understand it.
Let's get the numbers correct. Apparently it was a far larger difference than 4,000,000 votes:
That's a difference of 7,052,120 votes. But the most important mistake you made was compating the difference in votes to the total amount of people living in the US. That is incorrect, since you should compare the difference in votes to the actual number of people that have voted. As you see the 7 million votes of difference is almost 10% of the votes Trump received in total. That's what we can call a large amount.
From the total number of voters (158,383,935) this is 4.45%
Even when using the previous -incorrect- number of 4,000,000 votes, it would still be 2.52%
But anyway... 7,052,120 people is still a lot of people....
