How much do they need to make? If they made an average of $1/user, would that make them profitable? Having more people download your software, or having additional vendors ship it on netbooks, etc., shouldn't increase your costs by much.
Default search engine provider + app store = tons of $$$ with first world users.
I always wondered why they didn't put an ad during install process. There could be a google ads type of system where people could buy ads and get served impressions in installations. Or something like that. There are numerous ways to do this.