A crazy taxi company that does not own its fleet and is at the mercy of randoms who find the service exciting and worth the cost. As soon as people get bored with Uber and Lyft they will collapse like MySpace. This is why I NEVER invest in websites or services that depend on user generated content.
At the mercy of randoms? I'm not sure. With a valuation this high, marketing is a piece of cake. Also, once widespread adoption has been maintained, the network is taken hostage and/or is too unwilling to jump boat (see: Facebook with the greater mid-older generation). One shouldn't make the decision, in my opinion, to refrain from investing in certain stocks-type however fragile, especially because of the volatile nature of it that enables it to surprise the market. Also, insider information is valuable in the right hands and is always a possibility.