Search engines have to deliver relevant information, so there’s always a ‘grace period’ where new sites will be featured quite prominently – so long as the information is timely.
If, for example, you had a site on Tsunami relief, it wouldn’t make sense for it to go through the sand box, so Google et al would feature you for a space of time.
So a mega casino site with all the latest news and offers might, in theory at least, get a lot of exposure for a couple of weeks. But then it would drop – probably like a stone.
Whether you’d get your £ millions back is debatable. But if I was a millionaire with a penchant for experimentation, it might be fun…!