Success in writing depends too much on chance: What have you written? have you published it at the right time? what are people reading? is this the best book you could've written? could it have been better? What is trending right now? And so on and so on and so on. It is foolish to think that writing is a simple way to make money and it is wrong to tell others that it is a get rich quick scheme. The truth is if you make any money at all chances are it will be enough for a cup of coffee. Instead of having sky high dreams of being the next big author megastar my advice to writers would be to aim for something a bit more realistic: keep your day job but try and earn enough from writing so it can give you some extra pocket money whether that is a couple of bucks a week or a couple of grand a year.
Personally, I do not want to be super successful anymore. I think it would be too much pressure. I once read that JK Rowling was under so much pressure to finish the fourth Harry Potter book she considered breaking her arm to give herself a break. Yeah, that's fucked up. I don't want to be so successful that I cease to be a person and just become a cog in a machine that prints money. I mean it would be nice to make some money but I will settle for positive reviews online instead if I had to choose.