Want to use that cool new service (e.g., Stripe)? Sorry, not available in Canada.
Want to start a service that ships anything in the mail? Prohibitively expensive.
Want funds? Banks won't lend you anything and investors are very few and risk averse. $20-50K investments in web startups are rare and big news when they happen.
I love Canada and I'm not moving from it. But Canadian entrepreneurs have much lower chances of succeeding than American ones.
Can you make millions in Canada? Sure, but it's a much less likely occurrence. And if you do, it will generally be still less than what American startups can make.
This is why it makes no sense to start a company like Twitter in Canada. You can't sustain it. The best approach for Canadian startups is to bootstrap by charging money from day one.
So you can get a lot of nice "Italian restaurants on the web" doing SaaS and making good money, but don't expect groundbreaking innovation a la Google from Canada.
With that said, those who are already in Canada, like me, have no free pass. If you don't succeed, you can only blame yourself.
"In Silicon Valley they hand out money like candy" is not a good excuse for never achieving your dreams in Canada.