I've been getting gang raped in the NFL this year after dominating for three straight seasons. It's not a "waste of time," though. It's because I haven't put the effort into researching games that I used to.
There are no free lunches. That's the lesson to be learned from gambling, just like everything else. You can't just "read a line" and call it a day -- unless you're going to stick to fading Brandon Lang and/or Brock Landers and play nothing else.