> I am sure within 10 years every professional mathematician will use formal proofs.
They said the exact same thing 10 years ago - see e.g. https://www.vdash.org and the AMS Notices special issue on formal proof from around the same timeframe. Formal proofs are hard, sometimes tedious and not always very intuitive. They're slowly spreading out from the most "synthetic" subfields of math (the ones where you're basically working with unfamiliar "rules", but not with a huge library of proven results), but progress is really slow - definitely slower than many people would expect!
They said the exact same thing 10 years ago - see e.g. https://www.vdash.org and the AMS Notices special issue on formal proof from around the same timeframe. Formal proofs are hard, sometimes tedious and not always very intuitive. They're slowly spreading out from the most "synthetic" subfields of math (the ones where you're basically working with unfamiliar "rules", but not with a huge library of proven results), but progress is really slow - definitely slower than many people would expect!