I know some people who have had them for years with a regular sand bed. They like a good sand bed, but mine is only 4", they end up going sideways in the sand bed for almost 12 inches, so even the 6" would not be enough for them to go directly down. I have only had the pink ones for a few days, but the blue one for a while. As you can see, it burrowed into the sand most of the way.
what situation are you referring too? The ones you saw in regular sand beds, how deep were they, and how long did they survive? You sound like hey died, that is why I ask.