6. Interestingly, ChipMixer released with a "pay what you want" model, which is uncommon for mixers. Users were not charged a mandatory fee for mixing and instead could donate to the website. As any tech entrepreneur will tell you, donations are usually not a viable business model.
Exactly same Bitcoin amount on inputs/outpus would make tracking easier, so there's privacy incentive to make some donation.
8. After looking at ChipMixer's history, it's clear to me that they are being bankrolled by an extremely wealthy entity who doesn't care about profitability and has a lot of money to burn on making the service popular - millions spent, but revenue coming solely from small donations.
Is there are any data/survey which suggest donation amount is small?
15. Many large mixers have shut down due to legal action or unprofitability. Tornado Cash has been sanctioned, and their developers have been unfairly demonized. Yet - ChipMixer is running normally (on the clearnet, at that!) and no regulatory action has been taken whatsoever.
FYI, these days chipmixer only use clearnet as informational purpose.