Yes, someone could copy your idea and implementation.
But are they going to dedicate themselves to this full time for a year like it took you before you reached a poverty level income? Are they going to cold call 10 people per day for three months? Are they going to learn to write, nurture a following of people and provide content and value to those people in the hopes that <5% convert to customers? Anyone who starts by copying an idea probably doesn't have the same drive to make the idea successful.
The actual trouble isn't that transparency invites competition. The trouble is competition that already exists somehow using the transparency against you. Numbers, to me, don't seem like the type of thing that an outsider could use against you. Effective marketing tactics and growth hacks on the other hand can be gold.