You are right that the effects of internet advertising (assuming trackers etc.) on the individual can be understood as long-term, but in that case at least the

You are right that the effects of internet advertising (assuming trackers etc.) on the individual can be understood as long-term, but in that case at least the operator is undertaking two risks: 1) The long-term validity and usefulness of the data they are gathering. A user may be relatively net-savvy regarding the use of private browsing, they may rescind their consent on this or that advertising network to track them, their visiting son or daughter might give their device a "privacy clean-up", or they may be ironically so digitally illiterate that when their phone dies or they forget their passwords they just create a new Google account. 2) The legal risks involved in gathering, and particularly exploiting, non-GDPR (or other local law) compliant data. With non-consensual cryptocurrency mining, both points become irrelevant. Once it is mined, cryptocurrency is a pure commodity, regardless of legality and the consent or future opinions of the person whose resources were employed to produce it.