I’m as certain as I can be that few if any companies will be willing to invest (hundreds of) millions into projects to build some custom solution just to risk losing the bid in the end. And in top of that they would have a product that may have 0 demand elsewhere. Imagine if your employer told you they’ll hire you after you successfully deliver a project to test your worth. You’d think it’s a joke.

And anyway most costs are incurred during the lifetime of the project, after you proved yours is the best solution, with endless change requests, delays that require additional money, etc. The companies bidding usually have far more experience at syphoning money than the client has at holding on to it.