I don't understand your logic. You would have paid those high taxes regardless of Elterngeld. You didn't pay those high taxes because you received Elterngeld. Therefore, if you receive Elterngeld, you receive it from other people.
Yes, the government doesn't "give" money, it redistributes it. Some other people are paying for your Elterngeld. Even if in your head you assume that it is paid from the taxes you paid, the money you received for Elterngeld is now missing for other things, they are a loss for the rest of society.
