I think we somehow mix a lot of different things.
The yield out of / to Nigeria is not that high (compared to other african routes). The market is indeed huge but to achieve some profitability on that route (EUR-Nigeria) you need to be an airline providing connections (on your aircrafts) to the US (nigerian expats homebase) and also UK.
The market is huge but so is the concurrence as well ... AF
Only major airlines.
Believe me, if it was that profitable LX
would never have dropped the route. Especially LX
looking for every single penny and SN
trying to maximize its network.
might be profitable on that route but as for the others, I don't think it is a real goldmine (still if you look at it in a african profitability perspective).