That's precisely my experience.

I started my one-man consulting practice as a side hustle around 2006. I took it full-time in 2011. In its first full-time year my revenue was higher than the 6-figure salary I had the prior year. Since then, I've had ups and downs, but mostly ups.

Since then, I added five other income streams, but like you, the overwhelming majority of my income is from my consulting work.

I agree that such a high-skill service path is much more likely to succeed than more "sexy" ones the media loves so much. That's exactly what the book "The Millionaire Next Door" concluded after extensive research - most millionaires are owners of small businesses.