Sorry to hear about your loss in rankings.
I agree with your decision to not rely on a single source for your business model.
Having said that, I would not classify Google as an unstable nor unreliable model. They are the single largest source of traffic, so it would be unwise to give up on them. Instead, consider learning what you did that caused your decline in rankings, and adjust.
Google’s latest update targeted web spam, if you were relying on web spam to promote your website then you would have been hit hard this update. I suggest that instead of thinking of Google Search as being unreliable, think of web spam as an unreliable method of promoting your websites.
Sure, it takes more time and money to use white hat methods, but the results can be effective and far more reliable.