I'm sure it also helps if your target audience is in the wealthy subset of population. For example, a newsletter providing curated governmental data related to

I'm sure it also helps if your target audience is in the wealthy subset of population. For example, a newsletter providing curated governmental data related to animal welfare can't charge much because most animal welfare groups are struggling to operate on the small donations they get. However, a newsletter tailored for the opposite group (commercial farming) will make a lot more money because its audience is willing and able to spend 10x compared to the former. Same goes for finance vs human rights (not that they are necessarily opposed), and so on.