Because to become mindful, you need to make some effort and put some time aside to practice, mindfulness is often discarded as a time-stealing activity. In the end, we all have more important things to do, right?
In reality, mindfulness IS the important thing for you, because it allows you to live. It also benefits your mind by creating more space for meaningful activities. You spend less time worrying which in the end will enable you to see things clearly, and the same “more important” tasks seem to take less time.
Mindfulness creates time, it doesn’t steal it.