If you are a non-union, unskilled, blue collar worker who dropped out of high school, but has good native intelligence (passes a very challenging aptitude test) and a good work ethic, the military pay and benefits are better than you can get on the outside. If you are a highly educated, technically skilled worker with some experience, the military doesn’t even come close to paying what you are worth on the outside. Most people do not fall in either extreme. There are also many other reasons to serve besides pay and benefits. And pay and benefits cannot make-up for the potential of major injury or loss of life, if you do not wish to give up some of your freedoms and offer your life for your country.
Every year the Army Times publishes a putative pay and benefits comparison for various jobs in the military, and their assumed civilian job equivalent. This might be a good article to look at for some insight to your question. Benefits are assumed at a high level, even if the military member never uses that benefit. Thus I am assumed to have a benefit advantage of being able to use military health care, the commissary, and the Post Exchange, to the tune of about $10,000 in savings a year (which the Army Times would add to my annual salary to inflate that number). However, I live too far away from a post to take advantage of these “benefits.” The cost of gas to get to post would far outweigh any reduced price savings I would get. So my actual pay and benefits is lower than the “typical” pay an benefits the Army Times claims. When I lived in DC my salary did not go nearly as far as it does when I live in the middle of nowhere Alabama. A young PFC working in the Pentagon will find it hard to make ends meet, but the civilian secretary doing a similar job, with locality pay, will make far more. That same PFC at Fort Benning Georgia can live very well. It is probably better than the local business secretaries.