Are internet marketers building their business on quick sand.

Hi,
Now that I have reached the kind of income that allows me to live a comfortable lifestyle(although I cant say I am filthy rich, at least not yet) without having to work a day job, I am actually feeling a little scared.

I have many websites, ranked in google .
some have adsense ads on them while others sell affiliate products.

I am scared because a few days ago, my adsense account was disabled
and although I wasn't getting much for adsene( most of my income is from affiliate marketing )

But this led me to think, whether other sites of mine were safe.
A few months back, google deindexed one of my sites.
Maybe I had built my links too fast(using the packages sold in the wso forum, or maybe it was a link network that I joined.)
I am really not sure why the site was deindexed, but the thing is that one fine day my site was gone.

I have already built a different site which makes up for the income, but I am still not sure whether this is the way
to build a long term income which can stop with just one google slap or dance or whatever you call it.

Now, I keep thinking how many of you guys have this fear and
what are you doing to build a permanent long term income.

At the moment, I think the only guys having these kinds of income are the one selling services
for example the ones having link building networks,
marketplaces - where people pay to sell their products, their sites or their domain names
so these marketplaces dont depend on google or any other search engine for their income.

Please share your ideas about the solution to this problem.
what can people do to avoid depending on google or the search engines.

Regards,
faraz