Ok, Kestrels ARE good.
I just found it out.
Here's the way to get more money than you can dream of, in almost no time!
Step 1. Gather 10 million credits, or capture a Kestrel.
Step 2. Sell your Lightings.
Step 3. Go to a system where you can hire Lightnings, and where there's no 'Interceptor' AI ships. (Confeds, for example, attack you even if you attack a ship with no govenrment.) I do this at Lethe.
Step 4. Hire a Lightning. Go a bit away from the system stellars, so you won't annoy anyone, and then hail the Lightning. Release it from servitude.
Step 5. Immediately start firing at it. Do it carefully, you don't want to kill it, just disable it. Board the ship to add it to your bay.
Step 6. Repeat steps 4 and 5 once, then proceed to step 7.
Step 7. Go to a planet where you can sell your outfit Lightnings. Sol is a good example, at least in GS. Sell your Lightnings.
This will net you 2.8 Millions in about five minutes, if you hire/kill in Lethe and sell at Earth. In an hour, you'll have 33.6 millions, and you can do pretty much anything you wish with it. Do this for the standard duration of an EV playing sequence, 7 hours, and you'll have 235.2 Millions, which is enough to practically buy the whole universe.
The only downside is that repeating a certain pattern for extended amounts of time can get boring. But who cares about boredom, when you have a chance to get rich. Rich! RICH!
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It's funny until someone gets hurt.
Then it's hilarious.