That's dividend yield. If all companies stopped issuing dividends and instead spent the money on buybacks, you'd have a 0% dividend yield, but the same amount of money would be returned to shareholders without incurring a taxable event for remaining shareholders. Reinvesting dividends would allow for continued growth at whatever rate the ETF appreciated or depreciated, minus taxes.

> below CPI — so you are losing value even before paying tax on that income

All other things being equal, the value of your money is decreasing at the rate of CPI regardless of whether it's in cash or equities. Cash can be thought of as a bond yielding a return inverse to inflation, whereas equities are securities yielding a variable, unspecified return.

> where we are in the economic cycle

Determining this is difficult. Australia, for example, has not had a recession in 27 years.

> current corporate debt levels compared to history

Debt levels are at nearly all time highs relative to GDP (2000: 22%, 2008: 24%, 2019: 33%), but interest rates are also favorable for companies and close to historical lows (Investment grade OAS: 1.64%, High Yield OAS: 4.19%).

Trailing S&P PE is 20.72, which is at the top end of the regime from 1928 to 1990, but roughly average for the regime for 1990 to present.

In short, timing the market is difficult.