One thing that's not intuitive is the drag of management fees in the long run.

If I have 5% average stock market returns over 60 years and pay 0.5% fees, then $100k invested grows by $13M. If I pay 1.5% fees, it nearly halves. This is why I'm a fan of Vanguard and other low-fee index funds.

(1.045 ^ 60) - 1 --> 13.0

(1.035 ^ 60) - 1 --> 6.8