He also values his money extremely highly - not negative in itself - but, when he seems to value his ducats more than his daugther, you have to be suspicious. In certain ways, he is a stereotypical evil Jew of the literature of Shakespeare's period, racism and antisemitism being far more acceptable then than now.
On the other hand, he is loyal to his religion and has been badly mistreated by Christians.
Victims often become depressed, but sometimes they overreact and lash out in rage.
In literature, the victim is the most complex character.
It takes a special character to withstand a bombardment of abuse.
In my opinion, in the Merchant of Venice, Shakespeare creates a victim of mistreatment and discrimination, named Shylock but still manages to keep his human emotions.
His desire for revenge may seem vindictive, but it responds to a lifetime of being treated as almost subhuman.
He is also a widower who greatly prizes the ring given him by his dead wife, Leah.
However, in a nutshell, Shylock is a deep and interesting character that can be analysed in many ways.
On the surface he appears to be a bad person that does evil to everyone. Shylock is mistreated and discriminated against in a variety of ways.