Why is Vedanta so difficult?
Vedanta can come off as being confusing and difficult to learn because our ignorance is hard-wired and the truth is counterintuitive. It’s for this reason that it requires a proper guide. Would you try to learn theoretical physics by yourself? Also, unless you’re a spiritual genius, you will most likely never be able to learn Vedanta on your own simply by reading scripture. That said, you don’t have to be “brainy” to understand Vedanta. However, there are some qualifications:
Discrimination - Clear vision or the ability to tell the difference between that which is true and that which isn’t.
Dispassion - Seeing things as they are, free of projections. Dispassion isn’t about having an aversion to all sense objects but instead, evaluating them intelligently. Dispassion isn’t a “giving up“ but more a “growing out of.“ It’s the result of having Self-knowledge.
Discipline - The six-fold mastery of the sense organs and mind. The ability to (1) control the mind (2) control the senses (3) withdraw from sense objects (4) have forbearance (5) have faith in the teaching and the teacher and (6) concentrate. We “control” the mind and senses through understanding our relationship with objects, as well as with our thoughts and feelings. Discipline also includes the upkeep of the body-mind (our instrument for achieving spiritual success).
Desire (for liberation) - The individual, frustrated by worldly experience and multiple failed attempts at finding lasting peace and happiness, begins to look for it inwardly. With the gained understanding that true happiness can only to be found within, the desire for moksha becomes strong and the seeker, dedicated.
These qualifications are often stated because Vedanta is very subtle and the mind must be prepared. Many people who come to Vedanta have already spent years practicing Yoga (with a capital "Y") or a similar practice such as Buddhist Vipassana. They have already cultivated a mind ready to hear the teachings.
For preparing the mind, Vedanta traditionally recommends karma yoga and upasana yoga (today, taught as a modified version of Patanjali's ashtanga yoga). Many seekers who begin to pursue Vedanta find they often need to go back and get a refresh on the basics. Karma yoga, in particular, is often neglected by Westerners at the beginning and then picked up later on when they realize that Vedanta doesn't work only as an intellectual exercise and that their spiritual progress is dependent on it.
In summary, Vedanta is only confusing and difficult for a mind that isn't qualified and hasn’t found a proper guide capable of revealing the teachings. Learning Vedanta will still require a lot of work (just as learning any subject well does), but with the right qualifications and effort, Self-realization will only be a matter of time. Like most things worth pursuing, you have to learn to walk before you can run.