Income plays a big role in tabletop role-playing games. The options and assets available to a player are partially dependent on the money they have available to spend. In some cases, the assets they have also force a certain amount of income towards the players. In some campaigns, this plays more of a role since there are bigger expenses. For these kinds of situations, I hope to outline some tips.
Expenses Needing More Income
If you plan to have your characters managing a kingdom, they will need access to far more money and resources than a typical dungeon delving campaign. This will also be true if they will need to craft expensive one-of-a-kind items. If the players will be outmatched (see my previous article), they may also need more money to help hire help, bodyguards and to buy items to help tip the odds. There could also be role-playing reasons for doing so. Instead of raiding shiny things for their income, they may be getting paid a salary in order to serve an organization. A portion of their income may be taken to pay off a debt or something similar.
Though it may seem apparent, it's important to keep in mind the different ways players can spend money. If you want your players to spend money for role-play reasons, they need to have the money available and spending money should create results that are beneficial enough. If not, they'll take the best option and ignore the rest. If they have too much money to spend, money won't matter anymore. Summarized, if you want to make the players rich, they should still have reasons to spend money and things to spend money on.
Guides Are Suggestions
Dungeon Master Guides tend to have tables for rolling general things like treasure. It's good to remember that these are suggestions and can be easily manipulated or changed by the Dungeon Master. If more money needs to be sent towards the players, you can either increase it however you want or just take the maximum value from the table depending on the needs. A particularly rich dragon could have much more than the tables say. Make sure it makes sense in the narrative, including consequences that result.
Making Money Outside Combat
In my opinion, the section of the Dungeons & Dragons 5th edition Dungeon Master's Guide on running a business isn't very good. Instead, thinking about how much an enterprise (or castle, etc.) should cost and how much it should take to break even (I'd imagine most people wouldn't want an enterprise that takes 3 lifetimes to break even). After that, decide on possible consequences of good time period versus a bad one to use as a modifier on income. People tend to be fine with these kinds of things if they make of them themselves.