Then they took a nap for a long, long while. By then, no-one though again about building nests. At least, not until the next downpour. Immobility saves you from many dangers, but it prevents you from achievements. This is a reality for all sloths and many people.
People often prefer the safety of immobility to risk-laden action.
They may desist from marrying, out of fears that their spouse would have hidden and unpleasant attributes. They may avoid taking journeys, out of fears for their safety. They may refrain from taking new responsibilities, out of fears that they may not be able to cope with all of the new demands. They may even have grounds for their fears. But if you take that approach, you'll never get anything done in life.