it's true that bitcoin is being used in many bad sectors but literally why would it stop. bitcoin is a kind of money and money can be spent/transfer anywhere in the world in exchange for some product or any service. bitcoin is also used by deep web and most probably for all kind of crimes. we can see the recent ransomewhere attack which also demanded Bitcoin from common users.
Everyone can use money for illegal activities no matter payment is digital money like bitcoin,ethereum or fiat money. So bitcoin doesnt have any "deeply" connection with deep web activities..
yes that is right that it is different from person to person. but still we can say that most of the people are using bitcoin for legal purpose and may be there are some people who are also using it for illegal purpose. but still i will like to say that their number may not be too many because still very little number of people know about bitcoin.