Funding. Nobody has figured out how to fund development for large open source OSes outside of the enterprise realm. You crack that, you can have linux be installed by default on Desktop/Laptop computers, and patches that come as a result of that funding benefit the rest of the ecosystem as well. People will use the default, they will complain about it, just like they complain about Windows Update randomly restarting their computer, but they'll use it.
But also the share of people who own laptops or desktops continues to dwindle. Many people don't have and see no need for a computer. So they run Android, which is Linux, so I guess we're winning there?