If you have a mandate to generate returns (institutional, pension funds), you have no choice but to participate. You can't sit in cash forever as returns race towards zero [1]. You may flail and fail looking for that Alpha (perhaps even making wild private equity bets), but that's what you're getting paid to suss out as an investment manager. “As long as the music is playing, you’ve got to get up and dance.”

For equities heavy strategies, there is even an acronym to describe this: TINA ("There Is No Alternative") [2]

[1] https://www.visualcapitalist.com/700-year-decline-of-interes...

[2] https://www.investopedia.com/terms/t/tina-there-no-alternati... ("On the other hand, if bonds offer low yields. and illiquid assets such as private equity or real estate are also unattractive, investors may hold stocks despite their concerns rather than revert to cash. If enough participants are of the same mind, the market can experience a "Tina Effect," rising gradually despite an apparent lack of drivers since there are no other options for capital increase.")