The 747 has perhaps the worst cost per profit ratio in the game. The game works on diminishing returns, the more seats you put on the route the less you can charge for them. 500 seats one way means you cant charge that much to fill them all. Add to that massive operating costs, and you get fairly meager profits.
Last round i was making more using 990s and 737s on a route than i was making with a 747 on the same route, even if i was the only one on it. If there was a benifit i was marginal, and wasnt really worth the fuel costs. I operated afew token 747s for prestige only.
Origionaly the 747 was built for high density routes, more as a service to the passenger and the airport than the airline operating it. They where built to move people, alot of people, cheaply. to reduce airport congestion and make air travel mainstream and cheeper for the average citizen. Airlines couldnt fill them charging what the used to charge with 707s and the like. Prices sank and so did profits. Larger airlines could manage on the count of economics of scale and though identifying the proper nieche market of this aircraft. Other airlines tanked, or suffered because they aquired it as a prestige object. Back in the day, every airline had to have a fleet of these because they where big and sexy. Think Delta, Eastern, American, National, Braniff, SAS, Swissair, Aer Lingus. Airlines that no longer exist, or only operated 747s for a matter of months of a year or two.
The biggest pro of the 747 was its cargo capacity, which was and still remains the 747s saving grace. It was built with cargo in mind (elevated cockpit and short upper deck are there for a reason). However, we dont have any cargo in this game yet.