Savers aren't investors. Cash isn't an investment. Saving is when you keep your money in cash. Investing is when your money gets a job. Speculating is when you are predicting whether supply and demand will cause something price to go up or down (even though that thing will just keep on doing the same thing). The problem is cash is just an idea. It is stored potential. If money is kept in cash, investors will borrow it and put it to work.
If interest rates are kept close to zero, it means money is close to free for investors who have access to borrowing it. Savers on the other hand stop getting paid for their money. If inflation is higher than the interest rates, they are in truth paying for the privilege of saving. If interest rates become negative, lenders are paying for the privilege of lending.
Because this isn't obvious, it is called 'Financial Repression'. It is a stealth tax on savers. It is a sneaky way of reducing Government Debt and rewarding people who have borrowed to buy things. Most savers don't think in real terms. Inflation slowly eats away at both their savings and at the real value of debt.
I would love to see Governments experimenting with more direct 'free money' than keeping interests rates low and punishing savers. A Universal Basic Income can release the potential of people trapped from engaging with each other by empty wallets.