I save time instead of preparing for a test, after which all useless knowledge is forgotten

The same thing happened for me, I was frustrated when forced to learn things I knew I wouldn't need, and I like to learn things! just not useless ones.

having 8 tests weekly just empowers learning for tests a day ahead and forgetting all things afterwards

We need to also take into account that probable the things that are forgotten were things the person don't use and therefore, it is information not needed.

The bigges issue on that is that they are arrogant and hard to deal with, clearly because of the degree.

I am sure there must be people like that, but obviously not everyone.

Thanks for the great comment!