> Why would the company convert their main product into a competitor?

Thats easy to answer.

The reason why is because they'd get paid 10s of billions of billions of dollars for it, and otherwise their investment would massively lose a large amount of value otherwise.

Also, bytedance wouldn't be competing with tiktok anymore in those markets as they'd have sold it off.

So the choice is either to make a bunch of money, or to instead have their investment become worthless.

But would a new US-Tiktok not try to expand globally? Original-China-TikTok would then compete with US-Tiktok in Europe and elsewhere.

No, because "original tiktok" has a different name in China and doesn't compete significantly outside of China.

The tiktok that you know about is the international app that already doesnt compete with the rest of bytedance.

We didn't call the baby-bells an AT&T ban.

Because it was more than a mere ban, AT&T was dissolved.

AT&T corp was not dissolved in the '84 breakup. It continued to exist, providing long-distance service, but didn't operate any local exchanges.

Because the shareholders would most likely rather have X billion dollars from selling the company than 0 dollars from refusing to sell and getting banned.

It wouldn't be 0 dollars, though; the majority of their users are apparently outside the US. So the question is: how does the amount you could get by selling a US-inclusive Tiktok compare the potential future earnings of a US-free Tiktok? If the market prices it accurately, you'd sort of expect the former to be higher (a US-inclusive version seems obviously more valuable), but maybe they think the market undervalues them, or maybe prospective buyers would smell blood in the water because of the deadline and try to low-ball, etc.