(Most people have trouble wrapping their heads around just how huge consumer markets are. If you have 300M users - a la Whatsapp when Facebook acquired them - and charge them just $1/year, that's $300M/year in revenue, or enough to afford 1000 $300K/year engineers [or actually more like 1000 $200K/year engineers once you figure in overhead]. Similarly, if just one person out of every 100 acquaintances you know uses a product but they spend $10/month on it, that's about $400M/year. The challenge for consumer businesses is usually that they have to spend more to reach those customers and get them to open up their wallets than they make from each one, not that there aren't enough customers.)