IF yes IF that was actually happening i would have respect for those people, your argument is entirely based on a straw man fallacy, that's not what the military is doing currently and that is not what people entering the military plan on doing so it's irrelevant
The problem is that people believe members of the military should be respected for what they idealistically do. I have tremendous respect for anyone who chooses to defend me and my country whenever our rights are being infringed upon. Unfortunately that is not what a large majority of the U.S. military does. More importantly, those entering military service are very rarely naive enough to also believe this is what they will be doing. Of the many people I personally know who serve in the U.S. military, they all joined for one of the following reasons:
1. They had limited options in attending post secondary school or joining the workforce after high school, and military service would provide them with a structured lifestyle.
2. They wished to eventually reach post secondary school, but could not currently because of financial limitations. Serving in the military helps alleviate these financial concerns after service.
3. They were growing up in a troubled family/community and military service would help them "turn their life around" by helping them create a strong and more independent identity.
4. They held strong prejudices and hatred towards Muslims/Middle Easterns and military service seemed like a way to fight back against a people they did not like. This reason was not common but I definitely knew a couple kids who ignorantly entered the military for this reason.
While that list surely does not include 100% of the military force, I think it is fair to say that it covers a very heavy majority. Many people may join for a combination of other reasons as well, but these are generally the primary ones. More importantly, all those reasons are still self-serving in nature. Nobody wants to actually sacrifice their own life as it is often portrayed by troop supporters. They are no more saints or heroes than those who choose to attend a university in hopes of becoming the next great engineer, doctor, public worker, government official, or any other profession that also works to serve and better the general population.
And to your final point, the inability to meet the same physical demands that a soldier undergoes does not mean I should respect them. There are a number of professions which I would be quite inadequate at, as is true with all people, but the fact that someone can do something that you can't is no grounds for deserved respect. Just my two cents.