My dad is fed up with me?

he is reaching around his late 60's..... and im a 18yr old student whom is depedent on my family.... i do take care of my own expenses as much as possible,,, but he is like complaining why is he still working to support us.... i feel sad.... i care for my parents and try to be frugal as possible,, times like this make me sad..... pls help me find a gd solution.... or least cosolation words?