If you bought S&P 500 using dollar cost averaging during 1928-29, your average cost would probably be around mid 20s (S&P 500 was ~17 in Jan 1928 and hit the peak of above 30 in Aug 1929).

More than 20 years later in Jan 1950, S&P 500 was ~17. During those 20 years, S&P 500 never went above 20.

I tend to refrain from saying statements that are extreme or absolute as in ‘forever’, ‘never’, etc. because in this world anything can happen. I think ‘no one in the history of the world has ever lost if they bought the S&P 500 and held for 20 years’ is too strong of a statement, but given historical facts, the statement is sadly not true.

I do agree with you that investments should be made with long term perspective.

I’m just a believer of adjusting portfolio positions based on objective assessment on where we might currently stand in the market cycle and to prepare enough cash for possible big opportunities.