This question usually arrives after an experience. Somebody took a course or two, felt they had heard a lot and still could not do anything, and concluded the problem was courses. The problem is not always courses, but what follows that conclusion matters: if you are dropping them, you have to solve the thing the course was solving.
A course sells you three things in one bundle: information, an order for that information, and pressure to finish. The information is now completely free. The order and the pressure are the parts you have to build yourself, and that is the real work in learning alone.
Without courses does not mean without a syllabus
The person most likely to fail at self-teaching is the one who replaced a course with YouTube. They finish a video, open another from someone else with a different order and different vocabulary, and two months later they hold contradictory information and have built nothing.
What a course provides, and what you now have to provide for yourself, is a sequence: one thing after another, each step resting on the one before. I wrote about that order in how to learn digital marketing from scratch, and about what deserves to come first in what to learn first in marketing. Those two are a syllabus, not a source list.
The real free sources come from whoever built the tool
There is a large difference between a free source and an official free source. The official one comes from the company that makes the product, so it ages more slowly and contains nothing relayed second hand.
Take an example. Google publishes an SEO starter guide, and it states plainly several things that paid courses say the opposite of. The guide says keyword stuffing is against Google spam policies, that there is no minimum word count, and that E-E-A-T is not itself a ranking factor. Three claims you will meet stated wrongly in material somebody is charging for.
The same guide also says something about timing that saves you months of anxiety: some changes might take effect in a few hours, others could take several months, and you generally want to wait a few weeks before judging whether your work helped. That sentence is absent from most courses because it does not sell.
A clearer example: the limits written in the documentation
If you are learning Google Analytics, the official limits of the free tier are published with numbers. Data retention up to 14 months, 25 event parameters per event, 30 key events, and a BigQuery daily export capped at one million events. The paid tier reaches 50 months, 100 parameters, 50 key events and billions of events.
Those numbers are not trivia. A 14 month retention window means you cannot do a complete year on year comparison on the free tier, and that is a planning decision you make early. Whoever read the documentation knows this. Whoever only took a course might discover it a year in.
The rule: for any tool you are learning, find its official documentation and its own limits and pricing page before any course about it. Documentation is dull, and it is the truth.
The order: project first, sources second
The most useful change in self-teaching is to reverse the usual order. Instead of learn then apply, make it decide what you want to make, then learn what it needs.
In practice: pick something small and real. A page for a small business you know. A campaign on a genuinely small budget. A weekly report on a real account. The project is what tells you what you are missing, and that turns the sources from an ocean into a short list.
The difference in outcome is that you end up with something to show. That is what the interview is about anyway, which I covered in how to learn marketing without a degree.
How to tell whether you actually understood
There is a test simpler and better than any quiz: can you state the limits of what you learned?
Somebody who understands SEO knows parts of it are not guaranteed and the timeline is not precisely knowable. Somebody who understands analytics knows the numbers carry approximation and that retention has a window. Somebody still memorising speaks with more confidence than the subject allows.
If you catch yourself saying this increases conversion without being able to say under which condition and how you measured it, you are still at the memorising stage. No course fixes that. Doing the work fixes it.
What a course still does better than you
Leaving this out would make the argument dishonest. Three things self-teaching usually fails at:
1. Feedback from somebody better than you
You do not know what you do not know. Feedback is the fastest route to finding a mistake you have been repeating for a year. YouTube does not give you that.
2. A deadline
Free material is open forever, which is exactly why you do not finish it. A course sets a date, and dates finish work.
3. People learning alongside you
The question that never occurred to you arrives from somebody else at the same stage. That is a real reason, not a marketing one.
So if those three are what you are missing, the decision is not free versus paid, it is what you are paying for. I wrote about that from a different angle in why courses do not change your life. There is also a written comparison of what the money actually buys from the team at U Courses: Free vs Paid Marketing Courses.
The honest summary, and a realistic expectation
You can learn without courses, provided you build the three things the course was supplying: an order, a project that applies pressure, and somebody who reviews your work. Information is no longer the constraint. It is available, free, and more accurate than anyone relaying it.
But do not expect it to be faster. Self-teaching usually takes longer, because you spend time on the ordering itself. The realistic timeline by stage is in how long to learn digital marketing.
And if you do eventually pay, do it after you have built something with your own hands. People who enter a course carrying real questions get several times more out of it than people who enter empty.