Why the hell do you think that only the rich can deploy chemical weapons?
It's extremely easy to build chemical weapons out of household cleaning supplies. You might even have the ingredients in your house already.
The reason why using them is forbidden by international law is that EVERYONE, rich or poor, looks at a weapon that makes everyone in a city block barf up their lungs and agrees that it should probably be illegal.
That is definitely a less noble way to die than a bullet. Mock it if you want, but you're wrong.
If you wanna do some Marxism, focus on the exemption for domestic use of tear gas. Banning chemical weapons is one of the few good things the world has done.