Yes, it was basically just slowly growing as long as i owned it. But most my friends earned more than me, so it wasn't life changing (other than suddenly having time). I sold it after a few years for a low 5 digit amount.
I think the most important thing was to learn that i can make money without a "regular job". I haven't turned rich since then, but i have all the time focusing on projects i actually care about which is the single best job i can imagine.
But is it really? I am no designer so I don't know, but my weakest point as engineer often is a intuitive design. My affiliate sites would surely work better wouldn't they look like bootstrap templates.
I had to learn the basics of your job to succeed in mine, maybe it works the other way around too?
I think the most important thing was to learn that i can make money without a "regular job". I haven't turned rich since then, but i have all the time focusing on projects i actually care about which is the single best job i can imagine.