I think that running more sites actually increases your risk of income loss.
It may well increase the risk but more importantly, it spreads the risk.
I'm still working towards making a living from my sites (though I don't have a job) and would not be happy to have all my income from one site. I would also not be happy if all that income came from one source (ie adsense) As it is, I get about 70% of my income from my best site amd 70% of my income through Adsense. I would prefer both of those percentages to be lower.