If you have spent 10,000 hours testing you may or may not be an 'expert'. Depends on how much of the time you spent learning all about testing and constantly improving, and how much of the time you did the same old (perhaps even wrong) limited range of things.
In martial arts, it is said that 'there are masters of a thing, and then there are Masters of that thing'. This relates to testing expertise in that a true expert can not only do good testing in a variety of environments, but can teach (good) testing.
In martial arts, it is said that 'there are masters of a thing, and then there are Masters of that thing'. This relates to testing expertise in that a true expert can not only do good testing in a variety of environments, but can teach (good) testing.