Why buy from any of these sketchy Chinese platforms? I wouldn't feel safe giving them any of my credit/debit card information, let alone being installed on one of my devices.
Your first question is a legitimate question except that it contains the word "Chinese". Why buy from any sketchy British platform? Or sketchy Brazilian platform? Or sketchy Texan platform?
I'm not so much trying to defend Chinese companies. It just really irritates me that American companies get a pass. When I think about all the ways the Chinese government could weaponize TikTok against me or my children, it doesn't bother me as much as all the ways Facebook/Instagram/etc can and ALREADY DO weaponize my data against me.
I'm probably just extreme in this way though. When somebody asks me for a phone number of a common acquaintance, I decline. I will always get permission before I hand over that info. Any of these services could require a very short, clearly worded agreement that says they are allowed to sell any information they can guess about you; most of the masses will quickly agree to that and be annoyed that their screen time was interrupted.
That's not why.
But the stated reason is, "They are Chinese and controlled by the Chinese government."
Maybe I am naive to swallow this public reason, but I also think there are millions of other naive people and a good deal of them get trained by such campaigns to be xenophobes. So even if this is a fake excuse, it does real damage with the culture it builds.
Tiktok is directly used by Chinese military. Facebook/Google are indirectly pressured.
What kind of access and information do you believe they offer to the USA intelligence services? Why do you think it is ok for one government to have information about you, but not another?
How do you think the Chinese military can use this information against you or people you care about? How do you think the USA government can use this information against you and people you care about? How do you think your local school district or grocery store or your employer can use this information against you? What makes the Chinese military scarier than everybody else?