Being a Tank Commander will never make anyone rich.
Like all military jobs, the pay varies depending on the soldier’s rank. The base pay for a Staff Sergeant in the U.S. Army is only $30k per year. You could make more selling your Twilight memorabilia at Comic-Con.
However, Staff Sergeant is only the minimum rank required to be a Tank Commander. Most Tank Commanders attain higher rank, either before becoming a Tank Commander or shortly after.
There are also perks and bonuses involved, not to mention the standard military perks like ultra affordable on-base shopping and free housing, which can help a struggling soldier stretch a dollar like an Olympic gymnast.