put 100k at 4% vs what a savings account at a bank gives you thats a grocery bill a month in profit.
If someone is sitting on 100k in savings, there isn't much of a practical difference to moving it to a money market. The rates aren't significantly different. Some banks have higher savings rates, some higher money market rates. That makes other things your deciding factors such as the trust in a brand, quality of life, ease of use.
Remember, taxes are designed to benefit rich passive investors, so you gotta act like one.
4% is better than a 10 - 50% loss.