When you see a rich man who suddenly becomes poor or an average man who never grew above his current financial state, it's basically because they possibly weren't accountable for the money that was coming into their hands.
Being financially accountable entails that you delegate what your income would be used for and ensure you follow it up to the latter. It is one way that helps you plan well for your future since you can probably work on setting a particular amount out of your income that will probably go into short or long-term investment depending on what you want to achieve.
If you've not figured out how to hold yourself accountable financially, you shouldn't even think about making any real investment because it won't take time before you exhaust all the money in your hand and take your investment immediately. It involves discipline, proper planning, and the ability to stick with your plan. Big firms do it and if you take it seriously, even though your income might be little, the proceeds of the income will amaze you.
If you don't take your financial accountability seriously and want to allow everything to fall into place by chance, you will learn a hard lesson the bad way.
You should also not discount the education that a person receives from an early age up until when they enter the world looking for work. If somebody is taught early on the significance of money, instead of just learning some basic numbers and math, then they are likely to fair a lot better. You'll often find things like private education will cover this extensively, to fully prepare their students for the world of financial sharks that operates around them. Everyone is susceptible to things like advertising that is trying to pry money from our wallets every day and lots of people over extend themselves into debt, which can lead to a vicious downward spiral and make it much more expense to get back to zero.