This isn't a crime "just" to do with money. It's theft, fencing, and smuggling (and trespass?). Theft of national heritage no less, some of which has not been recovered - presumably they refuse to reveal its whereabouts.
Are some posters seriously suggesting if a serial thief lifted £20k from your bank account that you wouldn't want them to go to prison, because it was non-violent?
This is in stark contrast to most other threads about justice on MN - people positively revel about other criminals being tortured in prison.