That's probably a huge generalisation; but I wonder how many of those who behave like that by habit are too disorganised to make their own breakfasts, but also have a lot of money to fritter away.
Those who claim they are "too busy" or "don't have time" to have breakfast at home before going to work or taking their children to school, are really only admitting those faults!
I can't see how it can save time. If anything, going to a snack-bar, even a take-away one, takes longer than making your own and probably better breakfast at home.
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I have always made my own breakfast, though during a spell of working in a town a bit further from home I would also sometimes buy a hot pie and mug of tea from a snack-caravan in a car-park there.
Similarly, on my occasional long journeys to the North of England I breakfast at home but might stop for a mug of tea and a bacon butty at a snack-caravan on a layby near my motorway junction, some 70 miles from home. I refuse point-blank to buy food and drink in the motorway services - too expensive. I take refreshments with me.
As for the Mactuckybuckscosta* chains..... I would have to be pretty desperate to use any of them, anywhere, at any time of day!
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*[Costa is or was British; originating in London and later bought by the former, also-British, brewer and pub-chain owner, Whitbreads. Whoever owns either company now, Costa is no less up-price, down-value than the American ones, and no less pretentious with its pseudo-Italian names for over-priced beverages. I call it 'Costalotta'.]