In the 2016 election, few spectators realized Donald Trump’s data advantage until after he’d won.
In Data Science from Scratch, a book introducing data science using Python, Joel Grus said the following about R (pg. 302):
Although you can totally get away with not learning R, a lot of data scientists and data science projects use it, so it’s worth getting familiar with it.
In part, this is so that you can understand people’s R-based blog posts and examples and code; in part, this is to help you better appreciate the (comparatively) clean elegance of Python; and in part, this is to help you be a more informed participant in the never-ending “R versus Python” flamewars.