Haebom out of character

What could the grandfather possibly have said to Haebom for him to leave everything behind? Blackmail? Are we forgetting the Haebom's growth and persistence when faced with his adoptive mother threatening to break their relationship when she first found out about it?

Haebom stood resolute throughout all that, same with Taesung's father offering money to Haebom to leave his son, Haebom turned him down and fought for their relationship. What could a senile, close to death old man say for all that progress to crumble down and end up leaving his friends, parents, business, and Taesung behind??? This season is so unnecessary and its being milked, prove me otherwise.