Being an half-human in Egorian means to be regarded as third class citizens, even below sub-races such as halflings and gnomes. Marak hates that!
He is a people person. He wants to be loved, he wants to be accepted, like all other are, only because they were born as full fledged humans.
Marak has learnt as a child to hide his ancestry, to lie through his teeth about everything. He wants to be the center of attention. Being only half human left him with an empty hole for the other half, he wants to fill that hole and so he tries, with people, things, pleasures.
Wealthy people are loved, powerful people are loved, worshiped, well known. So, rich and powerful Marak wants to be.