How is there nothing wrong with greed? It's a negative emotion that makes you do things that are unnecessary only to get extra gains over what you are already getting or have gotten, and that usually makes you lose what you have already got which is why it is something that we should avoid at all costs. A greedy person can barely become successful at any venture, be it gambling, a business, or any financial situation in your life, be real and try to get what is rightfully yours or what you are getting out of luck but never get greedy.
The thing you mentioned at the end is exactly what greed is all about. When destiny is giving you the opportunity to get $200 which you can get immediately but you become greedy and wants to get $1,200 that only is a possibility and you might not even get it, you will even lose the $200 that you could get and might not get $1,200 as well.
This mindset needs to be overcome and anticipated, as expecting more in gambling often leads to the opposite result. We cannot control the website's system, especially in online games; instead, the system manages us. Humans cannot alter the outcomes predetermined by the system. It's a matter of luck – you might experience a big win if you're fortunate, but if luck is not on your side, you may end up losing more.