as much of a particular characteristic as is possible.
Eric is as competitive as they come and always trying to win.
as (something) as they come
Said of someone or something that displays a trait or characteristic to the utmost degree. Bryce is as talented as they come. Once you see him on stage, you'll agree.These strawberries are as fresh as they come. They were literally just picked!
as — as they come
used to describe someone or something that is a supreme example of the quality specified.
1991Daily Telegraph The petrol-engined V-8 was as silky as they come.