If you just describe software that solves a truly painful problem, people will ask "how do I sign up?" even if the software isn't built yet.
The key is to describe the problem better than the prospect can describe it themselves. The prospect can instantly relate and assume you have the solution.
Other software is harder to sell, especially "aspirational" software that doesn't solve users' top one or two problems. Often those are "solutions looking for a problem."
I never tried to convince anyone. I try to put my product in front of my assumed target audience and let them decide their self.
If people make money it's easy to make them spend some money. Hard part is to keep them spending.
Our software is for marketing
If it's worth anything, use it to market your shit.
First, you need to learn about marketing. Second, you need to learn how to position yourself which is something we expect from someone that knows about marketing, which you clearly don't have by the flagged reply in the thread. Third, use those acquired skills to marketing your marketing app.
If you’re in position you need to _convince_ — you have already lost.
Unless customers need your product so much they are happy to loose some money — your business is standing on the sand.
Even without a product people can buy the idea if you found the right problem and a meaningful solution.