If people don’t earn any interest these days, they need to save even more for their old age and can consume less as a result. Yes, but you do need to see the overall picture.
The size of incomes is the key factor when it comes to economic development and, in the final analysis, also savings: the higher are incomes, the more can be saved. And expansionary monetary policy boosts incomes, partly through employment and wage growth. Furthermore, there are not just savers; there are also borrowers who benefit from low interest rates.