I get they raise others' money, but which pension funds are being into this high risk stuff?

Almost all of them. They manage their portfolios like most other large fund managers albeit with a slight preference towards lower risk assets to ensure their short/medium term pension obligations are met, but they will almost always have an alternative investment bucket which VC will be a part of. They're also not interested in doing direct investments, so they'll diversify their early stage risk by investing in a couple of the more successful, established VC funds who spread the bets for them.

Quite a few. Due to underfunding they are under a lot of pressure to produce higher returns so they invest into VC and private equity.

lots of them allocate a percentage to alternatives, and with a low-return environment, there was a push to keep doing it. However, there's also been a counter movement of pensions moving cash out of alternatives due to mediocre performance after fees are accounted for.

It's a mixed bag really, a lot of it has to do with pensions sometimes being run by untrained elected officials, or them buying whatever bs a pe or hedge fund shop is selling them.

IMO, pension governance would be a better place to reform policy, as opposed to at the central bank level. I mean, should economy-wide monetary policy be changed just because of the arguably foolish behavior of some VC funds in SV?