You are lying.......
trading in a cutter nets 2-3 million round trip.
assassination missions your looking at around 2 million max per one.
You might make 10-12 million an hour....not 30.
If you spent more time understanding the BGS as opposed to watching netflix on a SC run, you might learn something.
Have explained this a number of times on the forum. I run two main freighters -
T-10 520 tonne capacity, Cutter 720 tonne capacity. I don't haul for anything less than 3 million credits per 120 tonnes.
Method, locate areas in boom state, more importantly an area that has a lot of stations within a 15LY radius and lots of factions, you'll find factions will generally pick 2 or 3 ports overall, a single factions cargo missions will generally be going to the same port or system. You want an area with plenty of systems in close proximity for quick trips.
My main area has always been the I-Bootis cluster, Pleiades cluster over the past couple of months, plenty of other areas in the Bubble.
A single run takes around 8 minutes, my T-10 is capable of holding two 180 tonne missions, and a single lower tonnage mission. My Cutter can hold four 180 tonne missions. Each mission pays from between 3 & 7 million credits, lets stick with the lower scale. That is 12 million per 8 minute run in my Cutter.
System state commodity trading in a Cutter makes you in excess of 4 million on a single trip. Medicines is a good starter, filter for systems in need, the burning orbitals also pay a premium.
A typical 180 tonne haulage mission, endless supply in the regions I trade in whilst allied.
3.5 million for 520 tonnes. A cutter will easily push that past 4 million
You cant just stay in one place forever, for example my main destinations around the I-Bootis cluster were in civil war etc, I traded in weapons for a bit, then moved on. Recently went back and they have good missions again.
The devs gave us system state filters, and we'll have additional tools in the future. I'd suggest you start learning to use them.