If I got the value doing something else, than that something else has returned its profit.
I'm not saying it was perfect as it was. I'm saying nothing earns quite enough. I'd say a 25% or even 50% buff to earnings other than mining would improve things quite a bit. The risk of combat is high compared to its rewards, exploration pays out better now but it's still not great, etc.
https://inara.cz/cmdr-fleet/56635/
That said, the expensive/large ships actually are pretty bad for generating money, imho. At least in proportion to their costs. I can probably do more in my Mamba as far is bringing in combat money than a Cutter or Corvette, mining is currently better in a Krait MkII, due to speed of the ship vs a larger ship. Only a jump-range fitted conda is best for something, and mostly that's just getting elsewhere to get engineering materials. That's a whole 'nother kettle of fish, however.
That's actually pretty sensible itself, in assets. I tend to keep ships long-term, however, as you can see in my above link. As it is I'm thinking about selling off a ship or two...