Why do less knowledgeable people think they're smarter?

It is a Psychological defense mechanism that prevents people from blowing their brains out thinking they are stupid compared to others. Plus, as one person explained to me, it is like the glass half fill example. Most people look up and think the end of knowledge is where the water line is but the smart people know it extends to the rim of the glass and not the end of the water.

If you read some of the studies like the one done by MIT, you will learn how most people do feel that they are smarter than they really are. When pitted against others, some who finished last admitted that they lost BUT blamed it on the tasks they had to do and knowledge they had. Said it was more suited to the other people than them. They all had excuses despite finishing last at tasks that others did much quicker and easier with the same education background as they had.

Most people think what they know is the extent of what there is to know. The high IQ people know that there is a lot more we do not know than know.