To help explain how SEO is powerful than ads, we'll talk about how online ads actually work. Google Adsense or similar tools like Facebook® Ads have certain demographics embedded into them. Factors like age, race, sex, etc are considered to be the deciding charts. But, there is a limitation to the extent of the effectiveness of ads. For example, even if you're playing Fortnite every day, YouTube will frequently show you an ad to install Fortnite because you fit the demographic Epic Games® entered. This means that Epic is spending money to advertise to someone that is already using their product. Now, this is just an absolute waste of time and resources.
But, when it comes to SEO, you're advertising only to the people that are interested in services similar to the ones you're providing. If someone searches best vacation spots, the person won't be looking to buy a PS4, he's actually looking for a good vacation spot to take some time off. There's no marketing tool out there that can really go for the targeted audience like SEO can.