The results are the results - Due to the wonderful craziness of the American system, Trump can win the presidency even though he lost the popular vote.
But just because they didn't get their desired candidate, doesn't mean that they should just roll over and take it like a bitch.
In fact, now is the exact time when they shouldn't just accept their fate.
Whining may not be so useful/productive, but protesting is a cornerstone of a healthy democracy.
If you don't protest injustice (in whatever form you see it) when it rears its ugly head, then it is likely that you will see more of it - as the people in power (Trump/Republicans/whoever) will see that they can get away with more and more.
If you care about your country, you have to be willing to protest what you don't believe in - passively accepting losses doesn't help you/your country/democracy/freedom/patriotic-American-music-combined-with-exaggerated-flag-waving.