Here's a fact. BTC was mainly used as a payment option to the infamous "SILK ROAD". So yeah, criminals would prefer using BTC than dollars because of its anonymity.
Anonymity is not the only feature of bitcoin which makes criminals prefer to use bitcoins. Another important reason is that bitcoin is easily transferable to people residing on other countries and there is no hassle of payments.
Do people think that btc is more used in world of criminal, than the dollar is used?
There is no doubt that all the criminals and dark wold activities are being done in bitcoins. This seems a bit awkward for the people who love bitcoins but it is a fact which cannot be denied. If i am not wrong, bitcoin is more used in criminals activities than the good activities.