Because Google gave the best results for a long time.

and now, when they are not, everyone else's results are also pretty terrible...

They pay $30bn (more than OpenAIs lifetime revenue) each year to make sure noone does.

What are you referring to?

Search deals with mobile OEMs and apple(preferred engine in all mobile browsers) also paying off Mozilla for a start. Also Goog has had a first mover moat for a while before Duck came along.

That got outlawed in Europe due to anti-trust lawsuits. I don't feel like it changed Google's market share here.