Fraud can be proven. But its a process and its not as easy than just claiming something to be fraud. We (hopefully still) have a justice system, with due process for the same reason.
That $9B is just a number. Whether it is reasonable or not can only be determined by looking into the details:
- What accounts as overhead?
- What were decisions that lead to that overhead?
- Were there alternatives that would have costs less?
- Why and how were those decisions made?
- Can we learn for future decisions?
- Was there actual fraud?
- When there was fraud, why wasn't it referred to DOJ to be investigated properly?
"Administrative overhead" is not bad by itself. Outside government, its simply called "Operating Expense" and "Cost of Revenue" (not a concern of government luckily). I am certain, if you look into SpaceX' or Tesla's expenses, you would find fraud too.
Because Musk and his brainwashed followers can claim stuff on Twitter doesn't make it true. And it certainly MUST NOT be basis to destroy Democracy and democratic processes.