The top Bitcoin mining pools in China create their own mining ASICs in house for competitive advantage. You just can't compete without spending years catching up to their hardware designs.
Off the top of my head, data from 2 years back(things might have changed now). Bitmain, one of the top 3 mining pools, 90% of their revenue was from ASIC sales rather than mining.
As long as Bitmain has competitors, they should always be able to put out the best ASIC's to the public.
They don't sell their latest mining equipment. Why would they? They sell the mining equipment after they have no use for it and it's costing them money to keep it running.