Nonsense....been a B user since 2009. One winter a rim lasted less than a 1000 miles.
The drive train wears out much faster than 700c just by the very nature of being closer to the shitty roads AND going round more per mile. Tyres also wear out quicker again because there's simply less rubber.
And don't get me started on the open bearings on the BSR and BWR or the stupid 2 speed thing that hates Northern grit.
Been a Brompton owner since 1990. Have sold them since 1985. Have worked in three Brompton dealerships including the LBC in Victoria when it was the only one.
The bottom bracket of a Brompton is no closer to the ground than your hybreed . So it's no more susceptible to dirt. Neither do the chainrings turn any faster, nor does the chain travel faster or under greater load. Sure, the rear sprocket is smaller. I've never worn one out in spite of being big and fat and high mileage.
What kills tyres? Wearing out? In my experience it's the accumulation of cuts from glass that eventually renders a tyre fit for the bin. A Brompton tyre doesn't cut up any faster than a larger diameter tyre.
The problem with Bromptons is that people neglect them that's why bits wear faster.
And yes, the derailleur is sh!t for getting clogged up. But that's not what we're talking about.