Much Like finance, Gambling and sports betting has a lot to do with building solid quantative models to hold a successful and levered risk model that will ensure gains long term with measured risk in line with proper goals.
The differene between blackjack, sports betting, and other casino games and finance. Is that you have 1 historical data set to reference. This is knownas the Heraclitus Principle. So you can only invest in the same market one time wheras with roulette you can continue to put the chips on black.
So you must estimate and that is the most solid plan to follow with high probability. The size of your wagers should always go up with a high probability of winning and go down with a lower probability of winnning which follows strict logic.
Also, you need to save for a rainy day as anything is possible. This can be examined in something called the Kelly Criterion which examines the issue of where to allocate funds in high probability situation.
Also, a big gamblers fallacy that should not be overlooked is that overbetting and not being disciplined will always lead to ruin. Just ask Bear Stearns or Lehman about overbets. (40-1 leverage).