Political Spectrum 101: the extreme left and the extreme right are the same thing
Let's use the famous cows analogy:
Centre: you have two cows, you sell one of them and buy a bull
Extreme Left: you have two cows. The government takes them from you, hires you to milk them, and might give you some of the milk.
Extreme Right: you have two cows. The government forces you to sell one of them, and tells you exactly which bull you are going to buy with the money.
They are both just different forms of control, and both have their extremist followers
But hey, don't take my word for it. The most obvious examples are Nazi Germany (extreme right) and Communist Russia (extreme left)