A good question, thoughtfully answered here by Jon Bloom:
Jesus could have given the moneybag to Nathaniel, “an Israelite indeed, in whom there [was] no deceit” (John 1:47), or to John, “the disciple whom Jesus loved” (John 21:20), or to Levi, who had extensive financial experience (Luke 5:27). But he didn’t. Jesus chose Judas to be the treasurer of his itinerant nonprofit.
One is tempted to offer the Lord some consulting on good stewardship. Donors were financially supporting this ministry (Luke 8:3), and Jesus appointed the one guy he knew was a “devil” (John 6:70) to manage the money. But this was not poor judgment on Jesus’s part. It was deliberate; Jesus knew Judas was pilfering. Why did Jesus allow it?
Putting Jesus’s Money Where His Mouth Was
I believe Jesus was putting his money where his mouth was.