the dumb person could have went full speed on the road that goes the exact opposite way on their first try, while the smart person could have went at 66% of the dumb person's speed on the road that goes straight to their destination
in that scenario, the dumb person would arrive first if they realized they were wrong before 1/3 of the way through the opposite road, otherwise the smart person would arrive first
i don't think that's the most likely scenario, and even that scenario isn't certain since it depends on the speed of realization variable, but it showcases that the problem as you described it does not have a single answer
the lack of any numerical variables in your description is what makes it impossible to give a single answer for
