A maxed out Lykon Type 7 with 208 cargo hold trading standard commodities makes ~1.6 million credits/hr.
Your math is way off. First, maxed out Type 7 carries 232 tons of cargo. Second, that maxed out Type 7 normally makes between 2.6 and 3.6 mil /hr (depending on how good the trade route is).
Commodities cost are very expensive with a high risk typically a 5:1 ratio between cost versus profit.
It is a slow, poor manuvering with less weaponry one will probably never get on target.
It requires constant flying.
This part is true, freighters are just freighters - they are not very good at fighting.