In the Chinese open source community, there is this thing that I would call open source "zeal" or "calling" (开源情怀)
Most engineers are thrilled if their open source projects--a database, a container registry, etc-- are used by a foreign company, especially a silicon valley one. They'd tack on free labor on top of already free software, to fix bugs, resolve issues, all day all night. It's all for the validation and approval.
Implicit in this "zeal" or "calling" is an acute awareness that no one in the west respects what they do because everything in China is stolen or created by cheating. They are also aware that Chinese firms have been taking for free lots of open source tech to advance, but they want to create their own, contribute, and prove that their tech is good enough to be taken for free by foreign firms -- some nationalism, some engineering pride.
So if you want to really understand why DeepSeek does what it does and open source everything, start there. It's not a political statement, not to troll Stargate or Trump inauguration, or to help their quant fund's shorts on NVDA (though if that were the case, it'd be quite brilliant and savage).