I had a high school friend who was a fan of LSD. Saying it isn't addictive is a lie. He was constantly touting the benefits, which I didn't see in his life.
Having a negative impact on your life is not the same as being addictive. Eating candy bars can have a detrimental impact if you do it enough, but that doesn't make them addictive substances. Sounds like your friend was just a big fan.
Just because it's a popular food additive doesn't mean it's not addictive. There is evidence that that sugar is addictive, so your candy bar comparison may be moot.