Could you please give an example? They are popular but how come their token is not successful? I know some popular casinos but they don't have a token. Some of these casinos do have a built in exchange but I believe that what the op mean is he develop the three platforms separately.

It's not a casino that has a token and a built in exchange but indeed that combining all the three features in one platform is much harder and more complicated than having a single featured platform only but the advantage is that you can attract more people to use your platform as it has all in one solution and there is no need for them to go for other platforms just to do some of these features.

How to manage them?
You would need man power or staffs that could handle out on specific position considering that this is composed of 3 key areas then it would be sensible you would be hiring
someone who do have the skills on doing so.
As long you do have the money or budget then this wont be a problem but  as an owner or being that too realistic then its better focus out on exchange platform or
gambling/casino site yet these two are really that good for long term aspect if you are really that minding for long term operation but of course
success wont really be that an assurance yet everything would really be depending.

Managing the casino is the least of the problem. Its the casino that you may really have to focus considering the competition in the market. Several of this kind of casino didn't really become popular. The few are in the forum like the Betfury which I guess you can just do what they did. The usage of the token will matter the most after all you plan to create an exchange for your token anyway. Listing on some of other exchange will be a bigger hurdle.

Will the casino also share the profit?