When a person invests in a company, that investment can lose value, even a 100% loss of principal. When a person puts his money in a bank his principal with interest is guaranteed. I don’t see why both of these “incomes” should be treated the same.
Well, the return on various investments should reflect the various risks involved. The greater the risk, the greater the potential return.
By the way, it is a mistake to view putting money in the bank as anything other than an investment. If you put money into a Japanese bank, you are investing in the yen. If you put money into an American bank, you are investing in the dollar.
If you and your brother are each given an ounce of gold at the beginning of the year and your brother buries his ounce of gold in the backyard while you instead sell your ounce of gold for $ 1,700 and put that money in the bank, you are both making an investment. In a year, you can be sure that you will at least still have your $ 1,700 if it's been kept in the bank. However, in a year, your brother can be sure that he still has an ounce of gold if it's been kept in the backyard.
Which of you made the better investment? Which of you made the safer investment? You invested in the dollar and your brother invested in gold. How many dollars can you get for an ounce of gold at the end of the year? Has there been inflation or deflation? You can only tell at the end of the year.