I built an internet advertising network like Doubleclick back in the 90s — when they launched, they did it so well that I became discouraged and stopped working

I built an internet advertising network like Doubleclick back in the 90s — when they launched, they did it so well that I became discouraged and stopped working on it. In retrospect, if I had kept it going for the past 15 years, I'm sure it'd be a big business now.