The Han Dynasty's Liu Bei here also has only two hundred thousand professional soldiers, and this is due to the presence of Chen Xi. Moreover, if you really compare the income of Liu Bei's soldiers to that of Severus's Roman soldiers, the Roman side probably earns more, which is even more terrifying.
This is not because the Roman economy is exceptionally high or terrifying. To put it simply, Severus is indulging in warfare, similar to the Martial Emperor of Han's actions in the past, where it didn't matter about other industries at home; they only needed a large army.
This method sounds terrible, and its shortcomings are extremely clear. Economic collapse and national recession are considered good outcomes. The domestic situation after the Martial Emperor's late period due to indulging in warfare is well known without much explanation, and Severus is actually following the same pattern as the Martial Emperor.
