Some people don't have the skills or expertise required for the success of 'build it yourself'. They must pitch their idea to others in an effort to partner with one or more individuals with the skills to make it a success, or pitch it to people with the capital necessary (if the founder doesn't have the money to fund it themselves) to hire those with the skills.

If you have the right project and pitch, with determination you can attract developers to work for equity (initially) AND successfully find the capital investment (as needed).