The bot owner is also providing "ad space" to Google. Author pays Google to show the ad. Bot owner gets paid by Google to "display" that ad and for conversion. The bot themselves aren't getting paid for installing the application.

In a normal scenario, the provider of ad space would be a website or an application. Google would pay the owner of that space. On Youtube, that would be an ad served by Google paid to the channel owner.

I once did this by accident and without a bot farm. It was very lucrative.

What I did was create a game with an action button. Then I served ads right next to the action button. I didn’t realize people would miss click on the ads at a high rate, but they did. They fat fingered it, clicked the ad, I got paid.

I looked into it after a couple weeks because my click rate was crazy high.

One reason: It helps makes the bot accounts look more legit. It's why Facebook bot accounts like random legit pages.

Have to do the install to get paid for the ad click, right?

Could be black-hat vulnerability scanners and so on.

likely they run an ad intelligence operation which requires them to click to see where the ads lead

upping the clickthrough rate on a low quality property to get paid for fake ad impressions?