Both options work, but you have to choose one style depending on the stage and type of the startup.
If you are founding a new coffee shop, or a trading company, probably you should spend more time working on the actual problem. But if you are founding a future tech (eg SpaceX at its beginning) or anything that requires huge capital or fast scaling in team size, you should spend more time on getting everyone buying the story and provides you with talent and capital to actually solve it.
If you are founding a new coffee shop, or a trading company, probably you should spend more time working on the actual problem. But if you are founding a future tech (eg SpaceX at its beginning) or anything that requires huge capital or fast scaling in team size, you should spend more time on getting everyone buying the story and provides you with talent and capital to actually solve it.