I wasn't so fortunate with ads, but I didn't have much experience then, either. Still, ads sounded better than making people pay and risk missing having a less fortunate crowd try it.
With that being said, there is a nasty drawback: people will use adblockers to stop your ads. I used to swear by rewarded videos for this- it checked if the ad fully ran before rewarding. Other ads are either skipped or completely blocked using ad blockers or putting the phone on air plane mode.
Ads are phasing out right now, but I bet they will return as a valuable method for making money from games.