And no - some people didn't willingly and consciously switched to their search engine. It was pushed down their throats by browser vendors being paid-off by Google for setting it as the default one. Mozilla has overwritten user-changed search engine setting in Firefox with several updates.
Non tech-savvy users simply accept changes made in software they use.
"Engines like Bing" is an ambiguous term. There are better options than Bing.
Keep in mind that if paying to be the default search engine in a browser is illegal, then Firefox's primary revenue source is out the window.
If I give you only one reasonable option and you choose that, is that selection? What if this one option distinguished others?
They have indeed invested tons in r&d, but with excessively little results. Besides web search it's tough to see succeses that Google didn't buy their way into. Gmail, maps, ... maybe?
I'm really glad that YC brought this against Google but it should be clear that YC also enabled them. It's a lie that YC is independent from Google as it partners and promotes their engineers and Big Tech allies. They see the writing on the wall and their lawyers see this as a hedge against lawsuits against them. "We didn't cause this mess, see look! We're trying to help!" YC also doesn't serve American startups at all and their entrepreneurs strongly favors California or India.