When you are investing, you should not expect highest interest rates for saving the money and doing nothing. You will have to make best use of your money to get the best interest rates. When you are looking to do some activity using your investment leading to profits and gain on investments, you should not expect others to give you best interest rates without knowing whether you are doing a healthy activity that will benefit them or not.
When investing, everyone expects to receive higher savings interest rates or capital gains as a benefit. When you are leaving your money in the savings account with a bank, you are actually telling the bank that you are not sure what you want to do with that money. At the same time, you are sending out a message to the bank telling them that you are not sure for how long you will keep your money in the account and whether or not it will be used to generating any kinds of gains. You are also asking the bank to guarantee a payment whenever you demand it. Because, you will get the money when you want and the bank is only permitted to use that money as long as you have not demanded to withdraw that money, you will get lower interest rates. The bank is unsure about your money and it will not be willing to pay best interest rate on your money.