What you have to look at is what that 50 sp would do for you otherwise. Right now, 50 SP is not even worth .01. So you would have to upvote yourself much more than 42 times in order to get a better yeild. I don't have the resources with me right now to check, but chances are that 50 SP would only be an upvote worth lese than .001. That would mean you would have to selfvote 420 times in order to get the same yield. Seems like a decent investment to me.