Karma is an incredibly powerful construction. Although it is attributed to eastern "mystical" traditions, it fills a huge gap in the rationalist west's attempts to make sense of the universe. It provides a possible rational explanation for the apparently random way that the universe functions. As long as the Karma police are at work, people are not really rewarded for bad deeds (as they sometimes appear to be) or unfairly burdened with bad luck in spite of their good deeds and cheerful nature. Karma is the unknowable "cause" behind the inscrutable "effect" that everyone eventually encounters.
Karma also returns some modicum of control to the individual for what occurs in his/her life. As long as there is Karma, what you do does indeed matter. Your actions will have specific effects; you will always benefit from doing good and pay for doing bad – eventually. Somehow, it makes even the worst breaks bearable to think that we had some hand in bringing them about. As long as there is Karma, we are not helpless pawns in some unfathomable game.
Unfortunately, just because something serves a beneficial purpose doesn't mean it's true. The only truth we humans have is a rather uncomfortable one: no matter how hard we try, our puny little, poorly functioning brains are nowhere near the tool that is needed to figure out what's really going on in our universe.
Don't know if this helps at all Patrish. I hope it makes some sense to someone other than myself. Maybe if Pascal would have been born in India his famous Wager would have been made about Karma rather than God. I think it applies as easily.
Thanks for the question; have a wonderful time staring at the roof of the world.