system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do Microsoft & Google spend $$$ making free browsers?

What do they get out of it?
gpt
In the case of almost every browser developer, it's a way to draw you into using their other products.

With Microsoft, the advantage of Internet Explorer being integrated with the operating system was a smooth transition from your computer to the internet, thus promoting Windows to the user.

Google built its browser to offer better support to web-based applications, where Google has a nice stronghold. They, of course, want to draw you into using as many of Google's products and services, especially the paid ones, as possible.

Firefox probably has the most unique approach to making money off browsers. 90% of their money comes from ad sharing with Google, which is why all their search bars default to Google. (Much of the remaining 10% comes from charging mobile device makers for the right to use their software.)