I'm curious how investing on gambling websites work?
Let's make an example that website has 100 BTC of it's own capital.
Then an investor come and deposit another 100 BTC. Total bankroll of gambling website is then 200 BTC
What does this mean? Does the owner and investor share profits 50/50, or has the owner more percentage, because he build the website?
You can find all the information about that on the FAQ's on the investment pages of the sites. Depending on the site most owners take 10% of the profit amount for running the site and maintenance. Some of them take an amount based on the wagered amount, around 0.1% of the wagered amount for some sites.
The bankroll is the most important thing for running the website so charging anything over 10% depending on the game isn't a profitable investment opportunity for any investor.