How do you know this?
I know you've mentioned being evil before but still
I know because I actually inquire about why people believe in things. And, from my observations and conversatons, many of them just enjoy to say "I worship Satan" to see the reaction of religious folks or to deviate themselves from an apparent norm and make a statement about it. Few actually worship or even believe in any sort of Satanic figure.
I'm not getting this either, They hate people worshiping Satan, why can't people worship him? We ask christians the same thing and why they worship 'god'
Because God is typically considered All-Loving, while Satan is seen as a figure of hate and cruelity.