Wow, what a tragedy. I had no idea what this was about and didn't think to click on the thread until I saw that the title matched something I kept seeing in newsfeeds. My heart goes out to the loved ones of the deceased.
As far as Travis Scott's role in all of this: I don't know the guy or what he is about. It could be that he saw enough to have realized that something was wrong, and that he is a scumbag for not stopping. But that being said, Grapp's quote from Randy Blythe is dead on. The biggest crowd I have ever been in front of playing loud music is a few hundred. And even with crowds that size, I can vouch for the fact that you have no idea what is going on beyond the first few rows. I have been in front of bigger crowds doing low-key public speaking gigs, and even at those, you typically don't "see" what most of the crowd is up to, and that lacks the deafening music and blinding light show. The guys in DT know exactly what I look like, and should be able to pick me out in a crowd, especially JP. But I have been at shows where I am only a few rows back and am waving at John or James, and they just don't even see me. That's the reality of being onstage. As I said up front, maybe Travis Scott did know something was going wrong, or maybe saw enough that he should have known. But I wouldn't be so quick to assume, because there are a lot of variables that weigh against that. Now I have to admit, an ambulance making its way through the crowd is something extraordinary that is hard to ignore, even from the stage. But giving him the benefit of the doubt, he may very well have thought something along the lines of, "Oh, man. Something going down over there. But looks like the EMTs are doing their job and are on it, so I'm not going to worry about it. Hope they alright."
I dunno. Don't get me wrong--I'm not saying he automatically gets a free pass. I'm just saying there is a lot going on from a performer's point of view that we have no idea about, and about how extensive a role a lot of those variables could likely have had on him being oblivious enough to have not taken any action.