The staff travels because they host conferences around the world several times a year. Conferences I've attended many times, and which are more than full work days for the attendees and the staff. Typically a day at an IETF meeting starts at 9AM, officially ends at 5PM, but then side meetings, bar BoFs, impromptu hackathons, and so on, will take you to near midnight almost every day -- it's exhausting (the staff probably doesn't work such long days, but ISOC officers probably do). There is no time left for sight-seeing, except maybe on the one night where there is a social event.

They host conferences around the world because attendees to the conferences in question are from around the world, and because ISOC wants to attract more of them.

I'm prepared to listen to real arguments about why ISOC sucks. But yours are either uninformed or you're not explaining them well enough. My bet is on the former. ISOC is not a charity, just a non-profit, and they've done quite well at keeping the IETF/IRTF and related groups going for decades.

Another thing you need to understand is that most SDOs (standards developing organizations) are pay-to-play. ANSI, OASIS, IEEE, Unicode Consortium, ... -- all pay-to-play. IETF? Free to participate. You don't even have to go to the meetings. Sure, participation == time == money, but being so accessible is a wonderful thing, and it takes an ISOC to keep it so.