Honestly... 50% in 7 years is an impressive achievement, and far from being awful. People often compare IPv6 adoption to things such as HTTPS adoption, but upgrading to IPv6 requires hardware changes on both the ISP side and the customer side, and as we all know, hardware upgrades take forever. It's not unusual to see >10yo equipment running in the wild.
Also even for HTTPS adoption - it was introduced in 1994, and in 2010 even major websites like google and facebook were basically only bothering to secure their login page which is how Firesheep came to be. It was only really that illustration of the business need that caused anyone to start bothering, and despite that demonstration, adoption was below 50% as late as 2018
