I hate to be a party pooper, but I often wonder if it isn't more likely that the presence of DMT in mammals is not simply that it exists in trace amounts as a precursor or byproduct of the biosynthesis of serotonin or another related neurochemical, and that it doesn't actually serve a useful evolutionary function. I am less sure of why it is present throughout the plant world, but given that it is a relatively simple molecule composed of elements that are fundamental to the natural world, I think the actual explanation is probably a lot less romantic than "it is a vital part of the fabric of reality". I think it is remarkable at revealing aspects of consciousness that would be difficult or impossible to experience otherwise, and these experiences do seem to temporarily shift the paradigm of human thought in a way that seems to reveal truths about the self and consciousness that are usually inaccessible..... buuuuut DMT is so powerful and otherworldly compared to other psychedelics that it often seems hard to bring anything tangibly relatable back from the experience, other than "wow, so this is a thing that exists".
In regards to ketamine being a recreational thing, I think there are two things you could mean by that. Of course, there is the use of lower doses in party settings, which is undeniably recreational use and something that DMT doesn't provide at any dose. What I was referring to though was more simply the fact that the k-hole is a lot more appealing that breakthrough DMT simply because by the time I am deep in a k hole, I have already gone through a process of gradual detachment from my normal associative thought process and fear in the normal sense of the word would actually be pretty hard or impossible in that state, at least for any prolonged amount of time. But I'd still say the hole is only "recreational" in a very niche way that would appeal to people that seek these intense altered perception type experiences, much like with DMT. I reckon even the most serious spiritual seeker type users of DMT probably have to admit that deep down, they seek these types of experiences because they are really fucking fun and interesting.
There is definitely a lot of value in manning up and facing your inner self head on with high dose psychedelics that actually increase associative thought rather than the other way round... but imo that doesn't invalidate the value of the dissociative hole, which is a fascinating anomaly in the possibility of human conscious experiences that is quite distinct from DMT hyperspace.