According to emarketer (https://www.emarketer.com/content/google-remains-most-popular-us-search-engine), the monthly share of digital searches in the US as of February 2021, was as follow: 26% for Bing and 61% for Google.
A 26% of searches is something to consider. Not only that, but the price per click, and therefore, of conversions, tends to be lower in Bing than in Google. Of course, you will probably not increase your traffic dramatically if you only use Bing advertising, but by using both, you can cover a very good percentage of digital searches in the US.
