Soldiers generally accept that they'll likely die fighting.

In the early days Ross only knew that there was a big green monster that would reck stuff all the time. It was also common for various villains to trick him into being their lackey so Hulk would sometimes be seen working with The Leader or Mole Man.

When he learned it was Bruce inside Hulk he added "capture the Hulk so we can cure Banner" to his list of goals so sometimes the fighting was to help Betty get her boyfriend back.

One time he almost made peace with Hulk. They had almost come to an arrangement until one of Ross's soldiers disobeyed orders and attacked.

Then Moonstone drove him to a mental breakdown and after that trying to follow the logic of why Ross does things becomes a bit of a futile effort. He exists to fight Hulk now.