That’t kinda stupid to be honest. Just charge me $50 for Firefox... you know what make it $100 per year and I will pay, just to avoid Chrome.
I don’t know how many of us are out there, but a large number of people don’t mind paying for the tools they rely on. I have co-worker who pay $100+ to get the email client they want.
How such a payment scheme would work with an open source project I don’t know, but find a way for me to direct payments to Firefox.