I have yet to get a ride in without at least 1 crash and I lose all the data
You should probably provide more details about your environment, Stephen - platform, OS, trainer, ANT+ connectivity, when it crashes, etc. Going to be tricky for Zwift to drill down without more info 
Just to offer some hope about the stability of the environment more generally, I am on Windows and have used Zwift maybe 20-25 times and haven’t had a single problem (apart from my Kickr briefly losing connectivity for maybe 5 seconds or so, which has happened twice with it automatically recovering both time).
your ride may still save on your computer so you can upload to strava
+1 on on what @Mark said. I have logged 25-30 rides on Zwift over the last couple of months and, other than one specific build that crashed on startup back in October or November, Zwift has been rock solid for me. I’m guessing your issues are related to some hardware or drivers that are specific to your setup. Send a ticket (via the “Submit a request” link next to your name in the upper right corner of this page) and they’ll help you out.
Hi Stephen,
Sorry to hear about your crashes! We have some trouble-shooting steps in our FAQ that might help you - they’re the quickest way of getting a resolution over just posting in our forums: https://support.zwift.com/hc/en-us/articles/202979045-I-experienced-a-crash-What-do-I-do-now-
As for your ride data, there is a 95% likelihood that the .fit file was saved up until the crash. Just look in your Documents/Zwift/Logs folder.
Mine has been rock solid as well. There was one time in November?Dec like Noel mentioned that we all had crashes but its been great for me.