Are you very experienced with either? As someone who manages digital media for a living and has dealt with 8 figure budgets, I certainly don't feel that way. However I'm very aware of how expectations are often not properly set by either company.
In their quest to reduce the friction to people's wallets Google and FB in some ways portray it as clicking a few buttons, creating a couple ads, selecting some suggested targets and you'll make a ton of money right off the bat. And perhaps that used to work to some degree.
The reality is that professionals tend to change or disable most of the defaults because they don't perform well or have other issues. We then go in implementing tried and tested best practices, knowing full well performance will still suck initially and that we have a long, expensive road of testing and optimization before we have things dialed in.
It is a tough business challenge because to some degree it is like trying to cram something simplistic like Paint into a hugely technical and complex platform like Photoshop. You just wanted to draw a damn cat, but there are all these confusing menus and tool bars, these weird layer things, and before you know it you've wasted an afternoon and end up just paying someone to draw it for you before you waste more time.
"I'm going to lose all of this, aren't I?"