I've spent $25k on X ads as an indie dev
My side project nslookup.io (a free online dns checker) got out of hand. I quit my job to work full time on it 3 years ago. I've since launched a DNS course (on Black Friday sale right now) for which I've run €21k (about $25k incl. VAT) worth of X ads.
Clearly I wouldn't have spent $25k if they weren't profitable. Over 1000 people bought my course, and most of them discovered it through the ads.
Start with 1 week on a $10 a day budget. That should give you an indication if X ads are potentially viable for your project. Less than 0.5 ROAS (revenue / ad spend)? Probably not going to be worth it, even after optimisation. Positive ROAS? Experiment, optimize and ramp up!
But that doesn't mean your product is bad if ads don't work. There are many factors that influence the successfulness of an ad campaign. But the quality of the product certainly is an important one.
Another is the sales page. I made mine before recording any lessons for the course. I wrote the course outline with these things in mind:
