They don't want to come and learn. They want to infiltrate and spy. They get rewarded for it back home. I'm sure some of them get Americanized in their time here and turn their back on the CCP but most do not. They know the CCP will come calling with a carrot and a stick. It takes a long time to deprogram a communist who was raised in the state dogma, and China has interest only in winning, and will play nice only until they have the advantage. I wish our leaders would understand this.
There is one arena where making a deal and just doing business is different than international politicsl dealings: in business, a broken deal you can handle by legal action or going to the enforcing authorities. In international relations, the only recourse for a broken deal is some level of hot or cold warfare. You have to be cautious with any level of trust.