Because the West doesn't bear the cost of letting India live in its fantasy world, Pak and China does. Of course, the costs that India can inflict on China are minimal but Pak is another story. I do believe the current army chief of the Pak army is a pro-US stooge. He has re-oriented their foreign policy towards the US. China has tried to build an oil pipeline through the country, but Chinese workers have kept being victims of terrorist attacks by various elements. This is typical ISI behaviour, they can always wash their hands and claim they knew nothing. The real paymaster is probably the CIA. This is an old model which both agencies perfected during the Cold War.
I think the massive overinvestment that China made in Pak (CPEC etc) was a huge blunder. China got very little out of it except terrorist bombings of its own workers. Pak did benefit quite a bit. The more you read about South Asia, the more you understand the best thing that can happen to that place is a big beautiful wall to keep its problems walled in, quite literally.
Being friends with China doesnt mean one has to be outright enemy of US. Thats just stupid and no country runs foreign policy like that nor China has ever asked any of its allies to make such choice. Not declaring US an enemy state doesnt make a very pro-Chinese establishment a US stooge. Lets avoid venturing into wierd Jai-Hind/MAGA realm here.
Regarding BRI, first, lets be clear, they are not donation or handouts. They are backed by various financial instruments, terms, conditions, interest rates, etc.
Undermining BRI (by attacking Pakistani and Chinese civilians associated with it) has been essential element of Indian proxies routed through Afghanistan. For now, China seems to have been rather passive about it at the big chess board level.
Regarding benefits of BRI, frankly, at this stage its a mixed bag because there is massive lack of transparency from both sides and some of the stuff is still ongoing.
Some infrastructure projects have been beneficial related to rails and roads for Pakistan and China both. If you go into line by line details of scantly available information, its not been bad for China. It has certainly been better than buying US T-bills.
Some are nothing but huge white elephants and a financial burden.The power plant agreements have been absolutely bad and anyone who signed those on side of Pakistan should have been hanged. Good RoIs have been made on those already by the investors.
There are other white elephant projects like Gwadar airport. There was absolutely no need for such a massive airport over there, whoever signed it on from both sides should have their heads checked, ideally hanged on PK side.
Meanwhile, some projects will bear fruit in the long term.
Anyway, point was, if you start picking thru fine details, its not blockbuster, but its aint that bad either.