As a result, iPads stay in use longer, get passed on to new users and serve for many years. Their average life span is likely well over 4 years and 9 year old iPads are not uncommon. It’s therefore very likely that the vast majority of all iPads sold are still in use.
So the true measure of success is not units sold but number of active (and satisfied) users. The iPad user base is probably around 400 million (about 27% of total active Apple devices.) The degree of activity is also telling and is reflected in the million apps built specifically for the platform.
And, taking over the traditional PC space is a big task:
It has not done that so far, much to the delight of naysayers. But this is not as big a failure as it might seem.
First note that the Mac user base itself is not nearly as big (110 million +/-10%). iPad could be 4x bigger in user base. The Windows base is larger at 1.2 to 1.4 billion but that resists frontal assault as it is deeply entrenched around enterprise workflows. It’s also bereft of profit.
Original source: [The iPad at 10](http://www.asymco.com/2020/09/16/the-ipad-at-10/)