I think it has much more to do with investors' sentiments. Canadian entrepreneurs are not comfortable; that's why they move to the US. But that's not because they don't like Canada. Moving is a big sacrifice -- they move away from their home and community, and also deal with the headache and uncertainty of US immigration. The ones I talk to who have moved down south, they miss Canada and didn't want to leave, but they didn't feel like they'd be able to afford the cost of living in Canada, and didn't think they could launch a successful startup there.
And the cost of living is going up, which is going to make even more talented Canadians uncomfortable. These days if you ever hope to own a house, you basically can't go the stable 9-to-5 route.
If investors in Canada were throwing hundreds of millions into moonshot startups the way that they do in Silicon Valley, probably most Canadian entrepreneurs would build those companies at home. But the investment landscape is such that the investors who have that much money opt to lever up on real estate instead.