I think they are trying to balance it between making as much as money possible, risking being sued for monopolistic practices and risking exodus. Microsoft once overplayed their hand and the anger and consumer dissatisfaction was so strong that people left Internet Explorer en masse.

So the best situation for google would be to have borderline monopoly where they pay for the existence of their competition and the competition(Firefox) blocks adblockers too by default but leaving Chrome and Firefox is harder than forcing installin adblockers through the unofficial way.

So basically, all the people who swear they never clicked ads manage to block ads, Firefox and Chrome print money by making sure that ads are shown and clocked by the masses.