I don't think the market has dried out just yet
Well, nobody can predict the future. Everyone with an opinion is just speculating.
Even if supply is going to be constrained in the future, as you think, I look at the rising interest rate environment we're in, heavily influenced by US monetary policy which is entirely out of our control, plus the debt-to-income ratio and wonder if real estate is in a bubble and is due for a correction or crash.
The Ontario economy right now is heavily biased towards real estate and its associated jobs and if that starts faltering, it's the bottom level of a house of cards that will tumble hard, destroying the "wealth effect" that's been powering all this growth the last decade or so.
If the market doesn't go the way you think it will, you're still on the hook for the delta between the contracted price and what you can sell it for, regardless of what your down-payment was. Even if your initial outlay was $75K, if the resale price drops below that, you can't walk away from your obligation to the developer. It's not even a true "option" like in equities, where the option can expire worthless and you lose your investment. It's closer to a short sell, where you could lose even more than the initial amount you put in.
You may also be caught up in a ripple effect if your fellow flippers can't afford to hold and wait, and have to dispose of their property in a fire-sale, causing resale values to plummet. How much are you willing to stand to lose on a $600K condo? $100K?
Anyway, nothing ventured, nothing gained. There are big rewards if you can read the market better than others and are willing to risk big as well.
Best of luck.