But really, infering the intentions of the users d/l-ing Cyanogen is ridiculous. A million downloads is exactly the tiny fraction of the population that you would expect to tinker and modify.
What do other users, who rooted their phone? I, for example, installed OpenVPN. I had to have "su" access in order to do that. But I do not plan to install CyanogenMod any time soon simply because of lack of the time.
So... 1 million of Cyanogen users is pretty significant number in fact.
OTOH, pretty much the only time Cyanogen gets replaced with stock firmware is when you're prepping a phone for resale or warranty work. Otherwise pretty much the only thing that people replace Cyanogen with are other MOD's.
What I'm saying is that 1 million number is firm -- always a consideration when targeting a market.
The other consideration is that a lot of the people jailbreaking their iPhone are doing it to pirate apps. (Although tethering is probably also popular). OTOH, many of the 1 million installing Cyanogen are tinkerers. So apps targeting those tinkerers may sell well. Targeting pirates is harder.
Are people unfamiliar with the notion of subsets?
Two sets doesn't have to contain the same type of items.
If the type of set A is a subset of the type of B, and the number of items on A is bigger, then A is bigger than B for every supertype too.