Didn't really pay attention': I told my friend he left millions on the table in retirement. Did I do the right thing?

A reader recounts urging a highly paid friend to invest more aggressively in retirement, arguing that millions were left on the table by underinvesting early while living frugally and maxing out 401(k)s. The friend kept much of his wealth in cash and then, two decades later, switched to a money manager, adopting a mostly self-directed ETF approach that split about 50/50 between the S&P 500 and the total market. The result—despite he now has a substantial nest egg—reveals how the opportunity cost of not investing early can amount to several million dollars. The writer questions whether challenging the friend’s habits was the right move and reflects on the balance between growth and spending in retirement planning.