Three reasons : Bribes, Kickbacks and Campaign Money
From 1950 through 1972 our corrupt government sent tens of thousands of our men off to die fighting communism. Yet just a few years after they were more than happy to help the greedy, rotten, heartless corporations outsource tens of millions of our jobs there including all our technology which cost the tax payers trillions over the years to help finance. Even high def TV was financed by our government back in the 90's then sent to China at no cost.
So you ask why did our corrupt government help to outsource so many millions of US jobs to COMMUNIST China ? Three reasons : Bribes, Kickbacks and Campaign Money. Basically they sold us out for financial favors.
Most American's would agree that all the politicians who helped this happen should be in prison including Bill Clinton and George Bush. I'd include Barrack Obama but luckily the TTP was stopped. And China has used all that money to build up not just heir infrastructure but also their military and soon will be able to take over the world.
Of course China did give us something in return for our jobs and technology, the Corona Virus which was a biological weapon that got out of control.