Online casinos are a crazy profit machine, super shady crap if you ask me.
You deposit, lets say 100$.
You're very oftenly get a deposit bonus, often +100$ more.
And there is always a nice "small text catch", that to release the bonus, you gotta have bonus amount played x30 (meaning, to "unlock" the 100$ of bonus, you gotta play out 3000$).
And thats like.. impossible.
You do can choose not to accept bonus and hope you'll be 1 out of 100000000 that actually gets some jacpot shit on some slot game but.............
So in short, not sure what OP played and did he had any bonus attached to that 50 he deposited, but I kinda think even if he wanted to leave with his 1300, he couldn't