I've heard apocryphal stories of companies seeing reduced clickthrough on search results when they've tried canceling ads for which they are the top (or only) search result, especially for extremely niche products. The claimed interpretation was that some customers were interpreting the ad as an indicator of legitimacy.

My guess is so that no one else can get it.

The last thing one of these companies would want is a competitor or some kind of unsavory hanger-on diluting their brand with a different message or viagra ads.

If a competitors ad ever showed above a perfectly relevant organic result, THAT would be pitchfork time. Until then, if advertisers want to throw money at Google at as a show of "legitimacy" for brand development, bully for Google.

Ah, so it's "new top level domains" all over again. Seems to be a pretty good way to vacuum up money.

> but what I cannot understand is why so many companies buy the topmost Google text ad even though their websites are already #1 organically?

Google's organic search takes lots of things into account, some of them personalization; a company that is usually #1 organically won't always be, and buying an ad makes it more likely that people will see your page first.

Citation need. Google is on fact doing the opposite. If a chrome user types a URL into the omnibox, they do NOT get a search. Whereas typing a URL into a form field IS a search.

Maybe so that a competitor doesn't?