Not to be harsh but the reality is that the three non-technical founders are not doing their jobs. Since they are not creating the product, their jobs would be to: fund raising, marketing, sales, and biz dev. But none of those happened after a year. As a non-founder your equity portion won't be great but you are the only one building the product; I'm not sure if the salary is worth it to stay on. It's best you chalk it up as a learning experience and move on.