Good point - but soldiers at least have a choice in enlisting and have some idea of potential consequences.
"Some idea" of potential consequences - yeah, you can get killed. If I was sure that I could get killed for morally valid reasons (like defending my homeland, your moral validity may differ) and not to defend oil execs exploiting poorer coutries, I would have less objections. I'm rather convinced that we will have some big war soon and I'll try to help defend my country first with my skills and if that's not enough, then at least as cannon fodder. BTW, I'm not from USA, we had forced draft until several years ago.
The military isn't for everyone, but I know plenty of people that came from all walks of life that joined for a myriad of reasons. The military is first and foremost about providing economic means for those that need a step out of their circumstances. You can agree, or disagree. The reality is most people argue college is the answer. Not everyone can get into school, and most won't get scholarships, lest we even look at the issues with post college placement.
The military is an option, one that is good for many. It can provide, shelter, food, generous pay, healthcare, and set you up with fully paid college.
Most of these things are readily available to well off individuals, so it's less targeting poor people as it is giving them an option they otherwise don't have.