Gmail is BETA

As many of you, I'm one of the lovers of Google's products. Especially their Gmail. I use Gmail more than anything. I rely on Gmail everyday, yet it still BETA. If it Beta, is that mean one day, it can go down without notice? Is that mean, they can go to ALPHA and lose all the messages on my Gmail? Does Gmail has the obligation to save all my data?

Should I depend my life on Gmail? Should I be worry?