Microsoft gave up developing their own engine, because that aspect doesn't make them money, and their engines were too far behind to bother investing into catch

Microsoft gave up developing their own engine, because that aspect doesn't make them money, and their engines were too far behind to bother investing into catching up. They're still making a browser, because it's useful even if it doesn't make them money. Mozilla's engine is modern and they have a clear revenue stream to subsidize its development with their browser revenue. But instead the browser revenue goes to dumb shit like mobile OSes (that definitely is too expensive), VPNs, executive bonuses, and basically anything but their browser or engine.