You might be on to something, but it may not be so nefarious at all.
When I first heard about the raid on Manafort's home, I speculated that the Mueller team had obtained a whole pile of evidence through the CIA/NSA surveillance that was orchestrated under the FISA warrant last year, but couldn’t use any of that evidence in a criminal prosecution because it would likely be thrown out of court. The raid on Manafort’s home may have been conducted to get evidence through "legitimate" means that they already had from the prior surveillance.
If Manafort had specifics of $75 million money laundering at his home, he deserves jail for stupidity.