Choosing VTSAX over VTSMX, due to its lower expense ratio, saves approximately $20,000 over 30 years on a $100,000 investment, allowing that money to generate further returns.
"over 30 years that investment would cost you 20 000 which is actually money that could have been also working for you over that 30-year period which could have made you even more money so even though vtsax requires more money up front it has a lower expense ratio of 0.04 which is where you'd save that 20 000"