If someone is truly comfortable, they will play. Children play, and learn and change at an incredbily rapid pace because of it. An uncomfortable child will suffer later in life for the lack of change/development they were able to do because they were uncomfortable.

Most of the time, most adults are teeming with discomfort. They may be capable of finding a daily routine that can be mistaken for comfort by virtue of being less uncomfortable than the changes they have easy access to, but that doesn't erase everything they have to deal with.

To change they need comfortable headroom, so they can at the very least suffer the extra discomfort of going through change with an insufficient safety net without breaking. The more comfort, the more secure the safety net, the more change there can be.