It’s simple: “In order to understand one person speaking to us, we need to process 60 bits of information per second. With a processing limit of 120 bits per second, this means you can barely understand two people talking to you at the same time.”
Because of such limitations, people find it hard to give the same amount of attention every time, especially in the kind of world we live in where there is roughly 300 exabytes of human-made information. It’s just information overload every single time.
To understand more about how our minds work, reach the article here: WHY IT’S SO HARD TO PAY ATTENTION, EXPLAINED BY SCIENCE