Thomas carries himself with dignity, is always clean, and dresses formally all the time because he believes his face is the face of his company. He is arrogant, greedy, unscrupulous, and ruthless, using his resources to inflict pain on others in order to extend his control over various businesses and resources, much like his father, Leviticus Cornwall. 
He is also incredibly vindictive towards the Van der Linde gang for killing his father. He disregards the safety of his employees.