I believe $UBER is well under way into its Wave 3 now, the risks are there, especially the concern about when they will turn a profit but they are focusing religiously on growth now and this is very much how $AMZN behaved for its first 15 years and they built a moat that is many years ahead of its competitors.
I believe Uber is doing the same and biding its time until autonomous driving becomes the main form of transportation and $UBERs growth could be exponential here.
As a good entry point, I think waiting for Subwave 4 to complete around $37 would be ideal.