I know a person who works on Bird's freight team, they apparently have been moving 2 full Boeing 747s of scooters (I estimate that to be about 12,000-14,000 based on weight) every day from China, at one point about $150 a pop). I think it's a sustainable model because after being shipped, delivered, and released (estimating about $80 more per scooter), it's ridden until dead every day on average 10 times (1.43mi/ride average, range 15mi average), earning it $10 plus $0.15/min, or ~$23.50/day. It breaks even after 7 rides, and they have at least 20 rides in them before they're toast.

I haven't factored in other parts of the economy, like oversupply, theft, premature damage, and payroll for the employees including chargers, but seeing they're in 100 cities with at least 3 million scooters on the streets being ride. I also based my guesses from https://www.bird.co/blog/birdyearone.