They're calculating with EUR 0.1 per user per month for targeted advertising. The "Pur Abo" (EUR 4-5 per month per site) are thus 40 times more profitable. The advertising has become mostly a mechanism to pressure readers into paying.
The question is, can you convince roughly 1/40 of your readers to pay 5 bucks a month if you don't use targeted advertising as the "threat"? Maybe, just maybe, non-targeted advertising would already be enough? Many people pay to get rid of ads, not of surveillance, after all...