Successful first flip...but should I switch to rentals?

[Dymond Shafer]

Aloha, we closed on our first flip and did very well (70k profit).  But BP podcasts, headlines about successful real estate investors and just about everyone I talk to says- building a rental portfolio is the road to true wealth.  However, my underlying concern has always been the horror stories of how these rental rockstars 'lost everything' during the recent crash.  It's only a matter of time before the market levels out, dips or (hopefully doesn't) crash.  So...questions:

How does one 'lose everything' during a crash/dip in the market?

I understand their property values decrease, but do their tenants all of the sudden stop paying rent?  Are buy and hold investors banking on the fact their properties will appreciate and never depreciate?