the 100k initial capital OP is saying is probably just putting a casino up and running. getting it to be successful is the most challenging for it needs more funds.
Let's say $2k weekly budget for bitcointalk signature campaign. That's $8k per month. With $100k it's only one years budget. How about others. The main source of traffic are the advertising networks where you will need to spend a lot of money. Affiliates will bring your clients but without massive advertising from the company itself, affiliates will not show interest too.
In any type of investment, the bigger the budget, the better. However, this does not mean that projects cannot be launched without providing an initial budget covering future years. $100,000 can be divided to launch the casino for six months, and the profits are added to the capital to cover another period. There are casinos that have succeeded in launching their own token, and other casinos enable investors to obtain a return from the profits of the platform in exchange for amounts deposited in the form of investments.
It really depends on the market of their casino and even though they already have spent $100k it does not mean that it will be successful. Having a good promotion is really a must as also customer service if a player needs some help with their funds and navigation of the website.