Contact people in their network that are knowledgeable about the potential market, or that are potential customers. Get their advice, network contacts or any other insight that can help to understand or test the real world market potential.

Get a deep dive in reports from McKinsey, Statista and other consulting or market research firms and try to understand market predictions and competitor analysis. Draft up a business plan. In order to avoid that the idea gets stolen, they keep the idea to themselves and do not discuss it with anyone. Contact venture capitalists that you share your business plan with, after they have signed a “non-disclosure agreement” that they will not be sharing your idea with other people.

Rather than analyzing the market opportunity, trying to develop a quick prototype that you can use to test the market potential with potential customers. In an idea world, you would be able to even finance the product development process with a consulting contract from a potential customer.

Spending 2 days interviewing and consulting potential customers and partners on their perspectives on an idea and seeing under which conditions these stakeholders would be willing or interested in sponsoring the project or committing to buying it.