That depends on your alternative options. The S&P 500 has averaged 6.6% real returns historically. Better than bonds? sure. Better than unleveraged global real estate? sure. Better than gold? sure. Better than PE? no. Better than leveraged rentals? hell no. Better than investing in productive capacity in your own startup? lol.

No one ever became wealthy from buy and hold index funds. The returns are relatively low because most people are lazy and it's the easy thing to do. That's why I split my time between active investing (https://grizzlybulls.com) and working on my private business ventures.