While Bing is not used nearly as often as Google for searches, it does have a few different benefits that make it appealing in some situations.
Bing is the search engine by default on Windows based computers and while most users change the search provider to Google, old users tend to just use it as they do not know how to change it.
This means that generally, Bing has an old user base. If your business is looking to target older users Bing is a great addition to Google Ads.
Also since Bing is typically a less desirable platform there is much less competition and that results in cheaper clicks.