Then it's a good thing that half the world's population lives within 500km of the sea, and that 80% of the world's population lives within 800km of the sea. As stated before, 500km is a day return trip by a car or truck, for door-to-door transport.
I seriously question your maths here. 500km round trip is 1000km total distance. You need to average 100km/h to make that journey in 10hs, which is pretty much as long as someone could reasonable drive in a day safety.
So in order to make that journey by your timetable, you need very good motorways in place, which is exactly what OBOR is doing.
Without that infrastructure already in place, 500km might as well be 5 million km if there are only dirty roads, or even no roads, and weak ancient bridges that could not hope to bare the weight of a truck empty, never mind crammed with goods.
I don't disagree that there needs to be investments in both inland and coastal infrastructure, but the vast majority of investment should end up supporting waterborne commerce.
This was the same model that was practiced in China. Develop the coastal regions first because they have easy access to the ocean. Because there is far more opportunity, profit and economic benefit than inland.
Problem with that reasoning is that you are totally ignoring all the investment that has already been poured into supporting water borne transport over the decades and centuries.
If you already have good infrastructure in place, adding more will yield diminishing returns on your investment.
The Chinese government is aiming for maximum bang for their buck here.
And they are operating on a timeframe of decades, not just the next quarterly profit report.
As the old saying goes, build a road and they will come.
We are already seeing this in Europe, with previously sleepy and in terminal decline towns and cities getting a massive revival and new growth explosion as a result of the China-Europe railway line stopping there.
In time, existing towns along the new Silk Road will grow to become cities, and entirely new cities will come into being along its route, much as the ancient Silk Road helped to spawn and sustain major population centres along its route.
All of these new cities and their populations will be fully integrated into a China-centric transport and trade network, so would become consumers of Chinese goods/services and suppliers for Chinese companies.
In time, these newly creates markets and trade opportunities will help western China develop and modernise, much like how sea bases trade did for eastern China.