I think the worst enemy is the bankers, crypto will be the end of banking, as there will be no need for them, thank God for that, The bankers are the biggest criminals in the world.
Everyone here on forum after earning bitcoins converts it into cash by depositing in banks , so banks are actually getting profit from BItcoins, so why would they be enemy to bitcoins .
In my opinions the biggest enemies of bitcoins are the users which misuse the advantage of not disclosing identities , to fund illegal activities.
The government would also become an enemy if they fear that their national currency would die and deny the acceptance of BTC in their country.