I only played french roulette for free here.
Casollo? Did not hear about this casino provider.
If you want to play there, be sure to find out if there is a license, deposit and withdrawal methods. You can also look for reviews on the Internet about this casino.
I play on a load of different sites, & have had a few wins, but nothing more than £100. I would agree with the comments made about the people who win alot spend alot. What I tend to do is go via a site called ** & then i spend the minimum required to earn myself some cashback! That way i don't really lose out on much, maybe the odd £10 here or there!
Every time you play in a new casino, check the SSL code by the html of the site - it should look like a green locker. That makes the site safe for you to play, also as mentioned, try to find opinions on that casino in other forums. Every casino you play should have a licence.
Hope this helps