I'm very much agreed generally, but in the case of somebody hustling by renting out their council flat, I'm not sure that the worst punishment is useful. This is probably not a wealthy person, and the damage done is theoretical and marginal. Making them pay it back entirely actually might be an onerous burden, it's probably mostly spent. I might reduce the amount by some token per night rented representing having to find somewhere else to sleep or having to share your space with a stranger.

Punishing financial crimes to a degree that could have a deterrent effect should start at the top, not at the bottom. Also, IMO, if the UK actually started doing this, its economy might collapse.