Having enough funds shouldn't be the only thing to focus on. Putting up a casino isn't an easy thing. It would require your skills and knowledge of this business and be honest, establishing a reputable casino will be hard if you can't meet the standards of most players. You have to make sure that you're also able to meet all the requirements needed to run a casino and where to get trusted people who could help you run this business successfully. You could risk a huge capital but you might lose it if you are not knowledgeable enough about what you are doing.
and there's marketing that is an endless spending of money for the casino to stay visible to users. you have to have deep pockets to make it. influencers are not asking tiny amounts of money to promote a casino. the casinos that made it to the top and stay on top for long spends tons of money for its promotion.
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.