I think you might be asking the wrong question. Instead of asking how much initial funding is required for Cryptocurrency Casino startups, you should be asking yourself how much funding is required to create a professional online crypto casino.
I think you would need an entire team first. Marketing, Legal, Development, etc.
That alone will set you back at least 100k per year. Then there are various costs like the regulatory fees, code audits and whatnot.
You could buy finished code and create another clone of some popular gambling website. But then you would just be another copycat that nobody is interested in.
Basically you should have at least 150-200k USD if you want to create something new, original and exciting.
You can make a shitty casino that you run with a friend in your spare time or you can have a big one with 50 employees. This is a rule for every business. In the game industry people make small studios and succeed with their games. You can find games on steam that look like they were made by 1 person with almost no budget. It's the same with movies and altcoins in the crypto space. I've met a guy who was running a bitcoin exchange operation all by himself. He'd sit in the office and run support for a single ATM and it worked! Now he has 2 employees and 2 ATMs.
I think he can make it with 100k if he knows what to do.