I usually don't try to interfer in others' affairs, so this isn't easy to write. You're heading into the snake pit, sonny.
Have you performed a Risk-of-Ruin analysis, based on the size of your bankroll and your 'standard unit'? How many upsets would it break your entire bankroll?
I've paper-traded your always-chalk approach; limiting myself to MLB baseball due to its market depth, low information-disparity and lower team performance violatility.
Using Las Vegas sportbooks moneyline odds at time of closing, I computing the win/loss based on actual game results from 4 MLB seasons. (Simple win/loss moneyline bets, no handicaps, no over/unders. No exotics.)
The results were dramatic. The percentage of winners you'll need to consistently make just to break even is nearly 98%. Thats with MLB, a low-violatility team sport where you'd expect more reversion-to-mean.
Vegas books are also much lighter on the vig than Australian books. I'd hate to even contemplate what kind of vig you're putting up with.
Remember the line (odds) don't represent actual probability of an event; its the perceived probability based on the action of either side.
The majority of recrational sports bettors are gut-feeling bettors, team follower die-hards who bet to highlight alligences, or herd-followers who put up juice for the chalk favourite.
You'll find real sports handicappers usually write about risking no more than 1.0 - 1.5% of their 6-figure bankrolls on one wager; they are content to consistently win 55% over multiple seasons. They have winning streaks, they have losing streaks. They have the bankroll to weather them out. The key is consistency of percentages.
They don't rely on the odds/line to tell them who is more likely to win. They rely on their own information and statistical analysis of game histories, players performance, coaching strategy, injuries news, venue-specific factors adn even the weather. Thats the source of their long-term edge.
There is no secret system, no magic formula. Just knowing the game.
Look, I have no dog in this fight; at the end of the day its your money, do what you want with it. Just don't say you weren't warned.