There’s a script the conspiracy theorists, and gun nuts go through it every time there’s a mass shooting in the US. This article on The Psychology of Conspiracy Theories blog picks it apart.

These days, a mass shooting in the news is basically a guarantee that in the next 24 hours at least 100 different people on the internet are going to use the red paintbrush tool in MS Paint to put meaningful circles around pictures of people’s eyebrows.

I used to regularly argue with a conspiracy theorist in his site’s comment section. I’d investigate his claims, quickly find out how reality disagreed with them, then get accused of being part of the conspiracy for pointing out its flaws.

It was fun, in its own dumb way. But he withdrew from being wrong on the internet, and now the United States has a conspiracy nut as its President.
Conspiracy theories aren’t just amusing stupidity any more, they’ve become weaponised, and they’re being used to create further division (and endanger people such as the students in Florida who are speaking out after they came under fire- their friends were killed- in the latest school shooting).