There is something I dont understand about this, maybe someone has a theory or can explain:
1.) Bitmain develops and builds CN ASIC.
Now:
2.a.) Bitmain (slowly or according to production) starts mining with them and difficulty rises.
or
2.b.) Bitmain just sells them and parallely mines with a certain amount because difficulty would increase to much?

In case 2.a. the miners go offline at bitmain and go later online at the customer. That should not increase difficulty.

In case 2.b. Bitmain would lose much profit. They could just mine as long as possible and keep the difficulty at an ASIC attractive profitable level and dont overproduce the ASICs.

So the problem in this case was that the devs forked away, right?

My question is, at what point do they decide to sell miners if there is no forking away?