Youths are usually the ones to instigate fanatical movements. The internet is full of far-left anarchist and communist groups too (esp. on Facebook and the like), who spout blinkered nonsense on par with some of the alt-right groups (although they're usually more well spoken / typed, w/e). Antifa utilises the internet heavily for their 'recruitment', as it were.
Young people are often looking for direction and a way to fit in, so extremist groups are easy go-tos because those groups will take them in regardless, due to their need for constant new members to increase their presence, and, as an end goal, power.
Young people can also often be very easily led, and if a young, straight white male feels angry at the world, it's all too easy to blame all 'Others' (in the Edward Said sense of the word) and thus join forces with more young, straight white males to lash out against those they perceive as negatively influencing their quality of life.
In regards to the specific 'E-Hitler' ideal, every side is searching for their Führer. Everyone wants a strong leader to get behind, someone who will tell them the solution to their problem, someone who will rescind their need to make complex decisions by themselves and allow them to be a cog in a machine, one where they feel at home. That's basically a core element of politics and the tribal mentality that drives much of culture at large.