Probably you using Gmail makes you more likely to use other google services, also they have scale, so if they get $10 of value per Gmail customer that's a lot more than Fastmail.
Also google is very bad at monetizing their products in general e.g. Google Docs has been around for years before Microsoft's cloud office offering, but they never seem to have bothered to turn that into a subscription based software package - which they almost certainly could have.
> very bad at monetizing their products in general
I'd guess that it's a support problem. It's quite hard to deny users support for paid-for products, and Google tries hard not to provide human support. It's expensive.
Obviously I'd be pleased if anyone has a better explanation ;-)
I think that's easier said than done. AFAIK Microsoft gets the real bucks from big business using their stuff. It would have been a very steep hill for Google to climb to compete with Microsoft in the office software market, doesn't matter that they had the web product sooner. You can see the same in reverse with the Windows mobile OS trying to compete with iOS and Android - which they seem to have given up on.
In addition, the difficulties of monetizing websites and software that seem to be doing great when offered for free IMHO shows how much stuff we don't actually need and only like to play with.
> Windows mobile OS trying to compete with iOS and Android - which they seem to have given up on.
Microsoft's strategy is to be cross-platform, which is why it has dozens of apps on iOS and Android, and supports Linux on Azure.
Microsoft's Windows strategy is to be cross-platform, with Windows 10 for "internet of things", phones, tablets, games consoles, all types of PC and servers.
Windows phones didn't sell well enough and the hardware lagged what was needed for Windows 10 (eg Hello and Continuum). However, there's still an ARM/smartphone version of Windows 10, so that door's not closed yet. There are always rumors about a business-oriented Surface phone
Also, Windows 10 was and is free for smartphones, so there's still room for Asian manufacturers to have a go. Even if they don't ship many units, it provides a fall-back if Google gets too aggressive on Android.
Also google is very bad at monetizing their products in general e.g. Google Docs has been around for years before Microsoft's cloud office offering, but they never seem to have bothered to turn that into a subscription based software package - which they almost certainly could have.