I believe age and accessibility has something to do with it.
A lot of teens (And some adult unfortunately) are rather selfish and kind of arrogant. They have yet to understand how important courtesy is. Especially with those special flakes who think they are so special and unique.
Combined this with how easy it is to access internet today, and voila, you have waves of insolent brats online.
Bad seeds always exist, but the rise of internet has made their presence that much more noticeable nowadays.