It's an unpleasant experience to deal with limited information regarding the project discovery phase. I can offer solutions based on my personal and my colleague's experience.
Try to educate the client even more during calls. Share with them some examples of how the discovery phase has helped previous clients achieve their goals, and show some work cases. Maybe he doesn't like the guide you provided? Try to offer another one https://solveit.dev/blog/why-you-need-discovery-phase. If the client still resists, make sure they understand the potential risks of skipping.
Try offering alternative solutions that can still ensure a successful outcome. For example, you could offer to conduct your own research to gather the necessary information, or suggest a phased approach to the project where you start with a smaller scope and build up as you gain more insights. Also, remember to set up clear expectations: if the client is determined to skip the discovery phase, set clear objectives regarding what you can deliver without that information. Be upfront about any potential limitations or risks that may arise as a result, and make sure the client understands that they will be responsible for any negative consequence
The last option: consider declining the project: Ultimately, if you feel that the client's refusal to provide information is putting the success of the project at risk, you may need to consider declining the project. It's important to prioritize your own reputation and the quality of your work, and sometimes that means saying no to clients who aren't willing to work with you in a way that ensures success.