This nails the issue with attempting to find (good) people who will work for free.
Good developers who are happy to work for free fall, IMO, into one or all of the following categories
1) They've made something that they had equity in, it's been sold, and they don't need to work - and they find Project X compelling
2) They earn enough in a part-time/contract role to have time on their hands, and they find Project X compelling
3) They have savings and find Project X compelling
Which points to the need for a rock-solid business case for Project X with a clear and reasonably likely/credible path to cash (or some other sense of significant reward) at some point in the medium term. And, furthermore, it needs to be more compelling than any of the many personal projects that developers usually have at the back of their mind. (Certainly, if I didn't have to work, I'd spend my techie time noodling away on ML and AI for the interest).
Inexperienced developers with time to spare may be more persuaded, but - especially if there is no clear sight of a goal they believe in - as soon as someone offers them a paying gig, they're likely to follow the money and leave.
It's probably easier to find the money* to pay developers than it is to find [good] developers who will commit to working on your project for equity.
* And - from experience - finding the money for a startup from external sources requires a solid, researched, market-validated plan, be it a loan, a grant or investment. Am going a bit Lean Startup here, but there are ways to firm up your idea and test the concept without needing to build very much, if anything at all. Affirming research, feedback and data is compelling.
While the execution of any idea is more important than the idea in itself, rushing to execute 'to work the business side out as you go' stacks the odds against a startup.