Well, I would not call it a huge success yet. Certainly it gained some traction and lots of people use it here (I'm from Germany), but in the past it was repeatedly shown that BlaBla Car's business model has no lock-in at all and that it will be very difficult to monetize their reach.

Predecessors of their ride-sharing platform here tried to charge (low) fees and users switched platforms rapidly or tried to circumvent paying fees (canceling of rides when drivers/passengers already have shared contact details). BlaBla Car could only grow to its current size because they did not charge anything.

This busines model can't be compared to Uber/Airbnb/... in my view and I really don't know who invested at this valuation and how they want to earn that much...