Investors know it's not profitable and operating at loss, yet they keep investing.
Uber is not lying and report their numbers accurately. They don't report unflattering numbers, which is telling, but still - it's not scam.
Otherwise known as "There's one born every minute."
Uber (and Lyft, et al.) are in competition with traditional taxis. There's a good reason taxis are more expensive, which is that taxis have to break even, at the bare minimum. If Uber charged what the service costs, there would be no difference in costs to the consumer between using a taxi or calling a Uber. It's the dumb investors which are making up that difference. They won't be dumb forever.