So are country clubs, and social clubs that organize fundraising galas and such. Joining them to make useful business contacts very probably works pretty well (I've not tried, but I've done some looking—note that the social clubs are usually exclusively for women—yes, even in 2021—but men attend the events). Tennis is still huge. Skiing. That stuff changes slowly, if at all—you and I just aren't part of it, so we can imagine it's some old-fashioned thing that's all but extinct, if we don't go looking for it.

Most of the shit from the now-ancient Official Preppy Handbook is still basically true, in fact, as far as I can tell.

The tech version of "where to meet people to make connections" is probably rock climbing gyms, right now. That'd be for barely-rich new money people connected to tech, or for programmers if you're looking to hire. Every group has their in-crowd preferences.