For some odd reason there's a wanting and needing for this to be true among many (especially in the alt health community). It's pathological. I can't explain it, other than I suspect there's a significant political and monetary motivation behind it all that's not interested in what is the truth and what isn't.
The avg person that buys into this is just a pawn. The reasoning follows; it has to be real because all government is bad. This is an extreme and simplistic point of view. Yes, govts and people do bad things, and yes, there is corruption and coverups and a failed medical system, etc, etc. But if you really look into it all, you find most of the Internet content purported as "proof" is just hearsay or explainable phenomena.
Chemtrails really are the prefect Conspiracy to propagate because everyone can see contrails; normal contrails persist (indisputable fact), and therefore everyone can feel threatened, but you can never touch or examine them. Those that claim to examine them claim they have picked up samples from the ground. In every case that I've examined, the samples were misreported or not proven to be from aircraft. Moreover, a dieing question I have is: How could anyone reliably collect samples from aircraft flying at multiple thousands of feet and GS of 400+mph? It would be hard enough to find a Humvee dropped from that altitude let alone microscopic fibers and spray molecules.