Is there a way to prove the real number of online users for other websites you mentioned?
Bitsler is among the top of the crop crypto casinos of the world , why does it surprise you that they have 700 online?
they are up there with Stake/Primedice , probably the two most popular casinos and rightfully so ,I must say
but once again , it is not only the online numbers that matter , it is the consistency what is important
people react to freebies and giveaways and promotions, sometimes numbers do not reflect the true popularity of a site and fluctuate wildly
some sites like bitdice or bitvest have under 100 players online at times , this doesn't mean that they are not a. popular b. making good coins ( and believe me they do )