> It's a 5 point scale, so landing a 4 or 5 on satisfaction on a 5 point scale seems significant.

No, it is absolutely not. Gallup is not asking "on a scale of 1-5, how would you rate your satisfaction?" They are asking:

"In general, are you satisfied or dissatisfied with the way things are going in your personal life at this time? Are you very [satisfied/dissatisfied], or just somewhat [satisfied/dissatisfied]?"

When it comes to surveys and social science the specific wording of questions has a huge impact on the results.

Sure, and 81% of people are somewhat satisfied or very satisfied. And the loneliness epidemic thesis was popular around the time that very satisfied was at its peak of 65% (when somewhat or very satisfied summed up to 90%).