1. Might be the person who helped was a relative.
2. His/her personality may be undesirable though the help was good.
3. Due to ethnicity.
4. The person became the life partner.
5. Haven't seen after the term of refernce.
6. Interpersonal relationship doesn't give chance to appreciate him.
7. Others hate that person.
It is clear that without their help you will not be in the status where you are now. As soon as we are disappeared from their eyes we forget about the assistance they have given, to get our eyes open to the world.
It could be your parents, a friend, your old school teachers, relatives, someone in the neighbourhood, your degree sponsorer.
At least say "I truly appreciate your help".
