The paid browser market essentially collapsed after Microsoft bundled IE with Windows for free. For example Netscape was $49. Microsoft famously attacked this with "Why waste $50 for Netscape?! IE is free!"

This doesn't make browsers today really 'free' (same like search engines aren't really 'free'). Browsers are incredibly complex to make and maintain. And the customers paying all these cost are the advertisers/third parties, not the users using them (entire reason for Kagi's existance is to create an option where user is also the customer).

Being able to pay for the most intimate piece of software you have on your computer makes a lot of sense.

As an example, Opera was payware for the first ten years of its existence. I remember trying out a demo of it included on a CD decades ago!