F-R-I-E-N-D-S

Just yesterday, I happened to pick up my sister's notebook in our kitchen table. Out of curiosity, I went checking some of the pages. I noticed some written items there. Some were just scribbled out. What caught my attention was the note entitled 6 Kinds of Toxic Friends, which include:

1. The fault-finder
2. The discloser
3. The self-absorbed
4. The double-crosser
5. The promise-breaker
6. The competitor

There were no description for each kind though. They were just enlisted. BUT such names sure sounded DANGEROUS... But WHY are they called friends at the first place? Can such people really be called as F-R-I-E-N-D-S when all they do is live by the name "TOXIC"?