“..you dug that hole all by yourself..??”
Actually, no they didn’t.
When the EU and the European Bank/euro (not identical with the EU) were established, there were certain economic rules established for membership. But the stronger economic powers (esp. German and France) were careful not to enforce those rules, for fear of weakening support for the “united Europe” concept.
Unfortunately, as Greece, Italy, and other members have shown, what that neglect really did was endanger the actual structure of the concept.