Yes, that is your pre-tax Basic Pay. And yes, we are underpaid. We will ALWAYS be underpaid.
HOWEVER - if you live within your means, and take advantage of the things we don't get shafted on, it is very easy to live a comfortable life. For example, with a few exceptions, the only pay that is taxable is your Basic Pay. Plus, if you serve even one day in a combat area, that entire month's Basic Pay all of a sudden becomes tax-free. It must be noted that many states do not tax servicemen.
Allowances, such as housing, sustenance, clothing, etc. are not taxable. Also, how many organizations will pay for your basic living expenses? If you buy a house, you can put your BAH towards it. All of a sudden, Uncle Sam is paying your mortgage, and you reap all of the benefits!
What if you put money into the Thrift Savings Plan? Well, if you put the maximum of 9% of your base pay into it, your taxable income is lowered by 9%.
Do I need to point out the cost of civilian vs. military health care?
I could go on and on, but the point is this: No, you will not get rich in the military. (As you correctly pointed out, that is not what we are here for!) Just do not use the Basic Pay charts as a gauge of how much you will make. There are numerous tangible benefits available to servicemembers that are worth investigating before you make your decision to seek a commission.