to get from zero to one, which i think is what you're referring to with your 'once you've got to 1' line at the end, you need to first find a market that's at zero; a product/service that doesn't exist. but that isn't enough; then you have to take it to one, a product that does exist. there are three piles here:
1. product categories that are technically feasible and profitable and where products already exist;
2. product categories that are technically feasible and profitable and where no products already exist;
3. product categories that are not technically feasible, so no products already exist.
anyone can tell the difference between pile 1 and piles 2 and 3. but you need a technical cofounder to be able to distinguish between pile 2, which is very small, and pile 3, which is enormous. and that's not something you do once; it's an ongoing process that happens at many levels of detail in your product, and even at the largest scale it's a gradual process of reduction of uncertainty, because you don't really know that something is technically possible until it's been done
then, you need to actually build the first product in that category, which involves identifying, prioritizing, and mitigating the risks that could destroy it. probably in banking a lot of this is things like regulators, market moves, and bank runs, but in companies built on software, a lot of those risks are software risks, and you need technical acumen to do this
as a nontechnical cofounder, what value are you bringing to the table? your family's money? invest in a vc fund, or start one, though without technical cofounders you'll waste all your money on companies in pile 3. your business knowledge? that's worthwhile in some cases. your leadership and management skills? likewise. but you're going to have to offer convincing evidence of something like this to be a good option for anyone to invest their money in