I actually know several people who have used only DMT and no other psychedelics,

To site an extreme example I know of someone who had never tripped on anything in his life.  He was however a regular marijuana smoker. 

His first ever experience with DMT was an IV injection of .3mg per kilogram.  He loved it.

Although he was a spiritual person who meditated often. 

I personally believe that the DMT experience can be very special for someone with no prior drug or psych experience.  IMO these people are even more prone to appriciating the authentically paranormal nature of DMT..

Speaking for myself I took acid and shrooms hundreds and hundreds of times before taking DMT

and none of it did much to prepare me for a high dose DMT experience.