I've been running PPC ads for highly targeted keywords for the last 5 years which have generated a ridiculous return. In general ppc is steady and reliable once you have you're keywords and ads running for a while and are well optimized.

On the other hand, I've recently been trying dropshipping, advertising the product on Facebook.

I did a small test for a unique product, I sourced it from China for around 5 usd and sold them for 25 usd.

People actually bought them on site even though Amazon has them at a much lower price.

Facebook literally knows people who are high spenders / frequent purchasers and will put your ads in front of them. It's actually stupidly powerful.