If you can't see the difference between showing an ad and mining bitcoin using your visitors' computers without their knowledge, you deserved to lose half your visitors.
Also I had a (sort of) premium plan that allowed to pay a small fee (2€/month to remove the ads and get some extra featues. When I made the BTC mining experiment they still had the option to choose between the free plan (BTC mining) or paying 2€ to get it removed.