Instead, the common currency has greatly benefited Germany: had the Germans retained the Deutsche Mark, their currency would be valued higher than the Euro is now, making their exports more expensive and/or lowering the profits of export industries.
Greece with its Drachma would have been a welcome victim for currency speculation. This was tried with the Euro, too, but it failed.
People also think in economic terms, but the Euro is a political project. Countries like Greece wanted to be in the Eurozone. It was not Germany's wish. It was the wish of Greece and the population of Greece also wanted it - not just the politicians.
Germany actually did not want to have the Euro itself, it agreed to the Euro to get the Reunification. But it agreed on the Euro to be a stable currency, not one that politicians would devalue to gain short term effects.
All pegs are a potential victim of currency speculation. The solution is to end the peg and let the currency float, as it happened to the British Pound/Deutche Mark during the Soros stunt in the 90s or more recently with the Euro/Swiss Franc peg.