Mass media advertising, at its best, makes a large pool of your Ideal Audience aware that when they are shopping around for a particular service/product, they should consider you.
Networking, at its best, gives you a personal connection with a handful of people from your Ideal Audience so that they think of your face when they are shopping around.
SEO, at its best, offers a chance to connect with a larger pool of your Ideal Audience who are actively shopping around.
Referrals, at their best, give you a great advantage over the competition when your Ideal Audience is shopping around.
Social Media Marketing, at its best, gives your Ideal Audience a peek at your personality in case they want to shop around.
Content Marketing, at its best, convinces a large pool of your Ideal Audience that they cannot shop around and you are the only one who can offer the product/service in the way they want it.
When you think about the ROI for marketing, make sure to consider the best-case scenario that each option offers you and pick the one that best matches your goals.