I was wondering the reasons that the Great Wall of China is sometimes considered a bit useless. So far one of the reasons I can think of is that the cost of it crippled China because all their resources and money was going towards funding or supplying the wall with resources and the workers with food. This also lead to rebellions from the citizens, and disloyalty from soldiers.
Are there any other reasons that the Great Wall was ineffective?
First and foremost, it is not ineffective by any mean. The wall itself was built since Qin dynasty, even before Qin Shi Huang was born, up to Ming dynasty to stop the northern civilizations from overrun China and it worked. Now, the northern civilizations had been raiding China for thousand years, long before Qin united China. They even came up with the idea of keep raiding China annually even if China had agreed to pay tribute to build up experience for upcoming wars against either China or other civilizations. There should be countless small raids into China that didnt go into history simply because there were too much and not worths to written down. In "Record of Grand Historian", Jin had to keep one of their best general on the northern border to keep the Huns in check and the Huns "visited" Jin many times in lest than 10 years.
Now, keeping an army ready to check on the nomads was not a good idea since the border was so wide and the nomads moved so fast, you simply cant expect to stop all of the raids. To effective stop the nomads, you would need many large forces always garrison near border and that gonna cost more than the wall itself. And even that may fail since fighting against the nomads in open battle were always a tedious job. You see, even with 40k troops, the founder of Han dynasty, a veteran of many battles, was chased and besieged by the Huns. When his wife was insulted by the Huns and wanted to revenge, the top generals talked her out of it because it would be suicidal.
The Great Wall was not supposed to be a wall so high that no one can pass. It was there so that the nomads cant just simply ride over and the very small garrisons on the wall would light up signal to alert the bases far behind the wall to mobilize to stop the intruders. That way, China stopped small raiding parties and only need to keep a few large bases to interfere the large raiding parties.
As for the money and worker to keep the wall up, in the "Economic" part of "Record of Grand Historian", the Han government changed methods many times but they all came to the rich can pay tax/foods and the poor has to either work for free, either build the wall or carry supplies. They even accepted livestocks like goats and material like bronze, silver or iron. It is a way the government used to keep the economy in check, especially when the inflation went up or down.