For the hobby? It was the internet.
I travel for work frequently and would periodically see 'working' women at the hotel bars. Also in Vegas, Honolulu, New Orleans and others, I would see the street walkers. None of that interested me, I was also married at the time and very committed to family.
However after my divorce and the internet, the whole 'hobby' scene completely changed my perspective. There were beautiful classy women that I could peruse, check reviews, and interact before taking the plunge. That's when it changed for me.
Then came Sugar Babies