There are professional bettors who make money on horse racing (eg: Alan Woods). They look at historical odds of horses, jockeys, weather conditions, track conditions etc and like these 'predators' on DFS use models to predict probabilities of runners winning. When the estimated probability of the horse winning exceeds the estimated final public probability by the track take, they bet, and bet big. Lots of data, lots of modelling, algorithmic, lots of domain knowledge, and fully automated. No need to scrape websites, totes will supply the latest odds take their bets programmatically.
Do you consider betting on horse racing as gambling? To be honest, for the professionals placing bets in this way, I don't (keep in mind it's very very easy to incorrectly place yourself in this category, and you will lose). But the vast majority of people betting on DFS do not, and can not, take this approach. For them, horse racing and DFS are very much gambling.