I realise that Google places ads in the native Gmail environment. However, when using a third party front end to embed the Google services, how does the company make money off that? When I use Thunderbird to access Gmail or the Google Calendar or when I map my Google Drive to the file explorer, how can Google profit from this kind of use?
The knowledge of what you do, where you work, who you talk to, what you eat, who your doctor is, where you shop, everywhere you go, what diseases or disorders you have, what kind of clothes you wear, what your family life is like, etc, are incredibly valuable to a company trying to show you ads. It doesn’t matter if you don’t see them through Gmail. Google owns so much of the internet, you’ll see them eventually.
Get your email from an email company, not an ad company.