Alternative idea: spend $1,000 or less on something that is unproven. You speculated and it turned out different than expectations. That's the name of the game. The only right answer is test. But you shouldn't expose yourself to so much downside.
App launch is a unique situation: you can only do it once. As such, pre-launch advertising is always unproven. You would have to have high confidence in the integrity of the ad network.
Since online advertising is essentially untrusted, with an entire industry dedicated to auditing its claims, I think the correct approach is to never try this form of unprovable advertising.
Was this really an option here? They probably aren't launching that many apps on the Play Store. So they had one shot to try out a pre-registration campaign to get a big app launch.
