I'd say marketing is where people who want to get rich doing little work go to fail.
Back when I was in college I was the publicity director for the college radio station which had a reputation for putting on poorly attended paper. I made at least 10 poster designs and hit the (small) campus with at least 500 photocopies. After doing this a few times a year for a year we had big crowds showing up every time.
If I'd tried to farm this work out to somebody else they would probably make 1 poster design and put up 15 posters and figure that was enough work and it just isn't.
Any kind of marketing is like that, it takes a lot more effort than most people think is reasonable, but it can very much pay off.
[dead]
Never forget Pareto! https://en.wikipedia.org/wiki/Pareto_principle You will find it applies to all facets of life, including marketing.