it is also the same reason why apple computers dont get viruses AS OFTEN. because they only hold less than 5% marketshare. why whould someone writing a virus want to do it on a computer that is so minimally spread? they dont... all products are suseptable to viruses, in one way or another. there is a way to hack everything. the security in place will effect the liklihood of a virus, one reason android is flodded with malware, it is open sourced and easy... microsoft and apple are more locked down, thus making it more difficult to spread a virus on.
Nope.
1) "As often" isn't true because there are currently no (zero) viruses on OS X. There are trojans, but like all trojans they rely on the end user to enable them to do anything rather than system weaknesses. The BSD subsystem that forms the foundation of OS X has been under scrutiny for over 30 years, a large percentage of its potential security holes have long been closed. Basically, it's incredibly, incredibly difficult to write an OS X virus. So difficult, no one bothers.
2) Mac marketshare is higher anyway:
Mac market share continues to inch up | Apple - CNET News
(and those numbers include hundreds of thousands of dumb windows terminals, such as ATMs, cash registers etc. that bloat up the numbers)
3) the "security through obscurity" thing is a complete and utter myth. There were viruses for the Amiga, yet the Mac sells more each year than the Amiga did ever. There are viruses for obscure phone OSs. Market share is irrelevant - and even if the mac did still hold just 5%, that's millions of computers - well worth someone writing a virus to e.g. extract keylog data.
You get viruses on a system when it has weak security and design flaws. Windows has a virus problem - and always, always will until it is rewritten from the ground up - because it's still tied to legacy code and back when it was written they simply didn't think about viruses.