Well, we live in a world where someone ran for president on the basis of "stopping welfare fraud" that turned out to be mostly a myth, so, you know, context is a thing.
As the article literally says, a whole bunch of people got sent to prison, that seems like pretty solid evidence.
The question is: now what?
Run the rest of them down? Figure out the total scope of the fraud, so we can enact countermeasures to prevent anything like it from happening again?
Fraud targeting social welfare programs is a grave crime; it strikes at public support for those programs. It enriches criminals very specifically at the expense of those people who would most benefit from the program.