Google Translate is a great product, but not monetizing it directly doesn't mean they do it out of the goodness of their heart. It is in their best interest to have access to as much information as possible no matter the language, and in that context a powerful translator is a priority, there is no way around it, and that is a massive financial incentive. That it also provides a great experience to keep its users loyal to their ecosystem is also a great financial incentive.
Also, don't underestimate taking away revenue sources from your competitors. If your competitor competes with you at A, but makes money at B, then taking away that B revenue stream affects their ability to compete with you at A as well.
There's Yandex which operates Russia's largest search engine (65% market share) which also runs Yandex Translate [0]. There's also Microsoft Translator [1], and Microsoft owns Bing, though MS Translator is a little different than Google Translate / Yandex Translate.
