They are in the business of buying and selling any zero-days. Tor browser primary goal is to be secure, unlike any other browser (which may still want to be secure but have many others goals). This zero day isn't exactly one either if you think about it, it only allow to run JS, which is a default feature on any other browser.
So they essentially lose nothing over it. People won't stop using internet and move toward written letters... they will just move toward other browser or update their browser, they will still be using something that Zerodium are buying and selling zero days for.
So they essentially lose nothing over it. People won't stop using internet and move toward written letters... they will just move toward other browser or update their browser, they will still be using something that Zerodium are buying and selling zero days for.