Sometimes if you give a good answer it will just sit there collecting points for all eternity. I did that a couple of times and I have several thousand points after a few years.
As someone has already replied, you slowly gather passive points from your earlier questions.
My account is from 2009, with 33 questions, and 120 answers and 10K points. It's a tough estimate, but I felt like I received my money's worth, sort of speak.
However, bare in mind that contributing was significantly easier 10 years ago, hence why most of my points stem from older questions and answers.