[Dalewyn]

Fund managers are obligated to act according to their fund's prospectus[1], of which the specifics will vary with each fund.

For a TDF (Target Date Fund), because that was brought up (Vanguard 2030): Both actively and passively managed ones must generally be managed such that shareholders can start withdrawing adequate funds (selling shares) upon and after reaching the "target date".

For an S&P 500 index fund like the one I mentioned and hold (SWPPX), the fund manager is required to imitate the actual S&P 500 index as much as reasonably possible.

In short, "don't have to care about long term success" is not a generally usable argument for fund management.

[1]: https://www.investopedia.com/terms/p/prospectus.asp

[parsimo2010]

If the prospectus says "follow the S&P 500" the fund manager is also not interested in long term success, they are interested in tracking the index.

But the fund managers tracking an index are not the main problem, they are just putting a lot of passive votes behind the funds that are actively working on electing board members in the interest of short term growth/profit (which brings more people to invest in their funds and gets them big bonuses).