The reason 747 was so successful wasn’t the amount of people it could transport. It was its range. Larger frame led to larger tanks and large range. 747 started

The reason 747 was so successful wasn’t the amount of people it could transport. It was its range. Larger frame led to larger tanks and large range. 747 started long haul non stop flights that weren’t possible with 707 not with two engine planes (before ETOPS). This has changed with longer ranges of A330/340 and 777 and has only exasperated the issue since. Airlines have simply right-sized their fleets.