If you left your money in a bank with low interest rates, 10 years from now, the money you left will be buying less of the same thing, lower purchasing power because of inflation. You can't do anything about it because all fiat is designed that way.
So if you care about preserving the value of your wealth, only hold fiat for expenses. The rest of your wealth, you invest in whatever suits you.
Another part of the savings should be put on the emergency fund. This will serve as buffer for when we encounter unexpected situations or when we suddenly lose our jobs. This will help provide for us while we are still looking for new earning opportunities, so we wouldn't have to touch our savings and investments right away.
I guess that is necessary, we have to save for the possible emergencies in the future, we should not let that we will be in desperate need of money due to our failure to save. For me, if you earn, you have to save, and you can do that if you will lessen your expenses and you maximize your income.
While we are young, we have to make an effort to earn as it can also help us to give a capital whenever we start to invest.