It might still not be the biggest scandal in the recent history of Germany: From 1993-1999 a company named Flowtex caused 4.2 BN Mark (roughly 2.1 BN € or even 3 BN if adjusted for inflation) of damages with a remarkably simple fraud scheme: They would claim to produce horizontal drilling machines (which allow you to e.g. put in tubing for cables without completely opening up roads) that they would sell to leasing companies they controlled themselves. Those companies would then lease back the machines to FlowTex, which would supposedly provide them to construction companies. The lease-back of the machines allowed the leasing companies to get bank loans to fund the buying of the machines. That alone would be legitimate, the problem was only that most of the machines existed only on paper, FlowTex simply sold the same machines over and over by just changing the serial number plates on them. So overall a pretty simple pyramid scheme which required FlowTex to sell more and more non-existant machines to cover the leasing costs it paid. When it eventually collapsed the scheme had caused a massive amount of damage to banks and the state. One of the reasons it could go on for such a long time was that FlowTex had good connections to the state government and the CEO Manfred Schmider and his company became so famous that they were considered "too big to fail" by banks and even the tax authorities, so they didn't act for a long time even though it was apparent quite early that something couldn't be right. In the end the Portugese authorities tipped off an investigation when they discovered FlowTex had supposedly bought drilling machines from a company in Portugal that went bankrupt a long time ago.
And while Manfred Schmider went to jail for a couple of years he apparently still managed to move a lot of his assets overseas and comfortably lives on Mallorca today. I'd not be surprised if Wirecard turns out to be a similar case, it's just hard to imagine that they really got defrauded by their banking partners and that a company of this size would simply entrust 1.9 BN € to some random lawyer based on the Philippines, this is almost certainly a cover-up story.