Yeah people seem to not understand several things about that. Firstly everything you’ve mentioned, but also if you’ve ever been around dumbfuck yokels you know they make the hell out of an IED. “So and so’s brother learned how to do this in Iraq” is absolutely the preface to a terrifying display in decent portions of the country. Additionally it isn’t hard to make a bomb, it’s hard to make a bomb you can detonate and survive doing so, which given by the shooter suicide rate isn’t a concern for these sorts. And I assure you methed up neonazis have been passing around bomb recipes like they’re cookie recipes for decades. And terrorist organizations like Al qaeda have attempted to feed instructions on this to Americans.
If you can get away with making meth you can probably succeed at making a bomb, the difference is once you detonate one you’re going to be caught and spend the rest of your life in a solitary confinement cell and everyone who helped you is going to prison for a long time.