Da’as Yochid, the Israeli wellfare system exists for altruistic reasons. They just do not want to support all the Chareidim in kollel anymore. Even the “evil” Yochanan Plesner suggested 20% of talmidim get exemptions.
So let them do so by passing a law! Until then, it is no different than taking a large mortgage deduction by taking out a bigger loan. A law, on the books, that is being exploited.