Recently I hit the 100,000 gold cap, and was wondering why there is one? I don't have a problem with there being one, I just want to know the reason :)
There could be two reasons I can think of:
1. They don't want long time players to have too much of a financial advantage over beginning players when the next expansion is released (less likely)
2. to encourage players to spend their money on housing items, training companions and the like. The moe they spend in game gold, the more invested they become in their houses and crew and the more likely they are to continue the game with a subscription or buying more crowns. (more likely)
I don't know for sure, but one of those (or both) would be my guess.
Host of the Talkin' the Plank Podcast, where we talk about Pirate 101 every Friday!