It costs a lot more than that. Airline tickets are routinely 500-700$ (eg. SF-NY or SF-Miami). Then you need a couple of nights of hotels on top. Add 2-3 meals per day. And suddenly you are looking at 1000-1500$ per person. For a team of 40-50, that's ~50K budget for 1 day of productive work.

Now compare that to an office lease where you can get. At an avg density of 200 sqft/person[1], you'd need 10,000 sqft. You can get that for ~500K$/yr[2]. You use that for 10 times in a given year and you are breaking even.

[1] https://aquilacommercial.com/learning-center/how-much-office...

[2] https://www.loopnet.com/search/commercial-real-estate/san-fr...