Amp was a reaction to Apple News and Facebook News: using those applications to read the news was a much better experience than using the web. Why? Mainly for two reasons:

1/ Apple and Facebook were hosting all the content.

2/ The content did not come with megabytes of JS and other unnecessary crap.

Amp is an attempt at saving the web, and Google is interested in that for the reason that you gave: they make their money from the web.