* Buy more money or income
* Invest More money or capital
Now let's understand the concert money, is a legal tender or recognised transactional exchange documents. It can paper type, coins or digital currency. For any money to increase from example one, there's a need to buy more money, now the idea of buying more money simply to savings and rents from source of income or business involved in. When you keep the policy of savings you're buying ideas of more money which power your future investment.
I don't know if there is a part of the world where money is bought. In my country money is earned. Bought the idea of buying money came to us as the government decided to go cashless due to upcoming elections and other reasons. In my country, cash became scarce and banks stopped paying money. People were using money to buy money in order to have cash.
For example, if you have a certain amount of money in the bank, the POS operators will charge more than 10% of your money to give you fiscal cash