To be fair, the money/time tradeoff breaks down pretty quickly - you've almost certainly used all the easy wins by the time you're even earning mid six-figures.

Basically, there are only so many hours of outsourceable stuff in your day. Once you've made the trade for cooking (eating out/chef/stay-home-spouse), cleaning (maid/stay-home-spouse/etc), errands, scheduling, minor research, and other miscellany (secretary), local transport (owning a car) there isn't much more to do.

If you really value your time, you can fly a private jet at the cost of maybe a few thousand dollars per hour saved, I guess.

And Warren Buffet, even in his frugality, does all of these things.

I think frugal here is relative. He doesn't care about status symbols and living a super extravagant life with huge mansions and yachts that other billionaires do. But I'm sure he has a lot of expenses that most middle class would not have.

If his car breaks down, do you really think he'll take it to the shop himself and start taking a bus to work?

Buffet is the exception that proves the rule.