Passive vs Active
Passive investing is considered best for most investors because markets are highly efficient. This means that information about the world is incorporated quickly into prices (sometimes in the order of microseconds), since market participants have a strong financial incentive to buy low and sell high. Your run-of-the-mill active fund manager is not going to be "nimble" enough to make investment decisions faster than high-frequency trading algorithms.
Market participants are trading to try to get an edge on each other, but in aggregate they will get the same market return passive investors get. Active investing means you'd be picking a fund manager with the hopes they can do better than half of the money invested in the market, most of which held by sophisticated institutional investors, by a large-enough margin to cover their high fees.
90% of funds don't outperform their benchmarks over 15-year timespans, and those that do rarely do it again in the next 15 years, so even that outperformance can be attributed to luck. That means your choice of active manager is essentially random, and you have less than 50% chance of outperforming. You can see then why getting a guaranteed "average" return (minus low fees) from a passive fund can be the best option.
US investments
You express concern about the fundamentals of the United States. But again, markets are efficient. Concerns about US institutions are already priced in to the market. Emerging market stocks, for example, will generally have lower price-to-earning ratios than developed market stocks, partly in response to their shakier legal protections. If new systemic issues with US financial markets come to light, the market will reflect that in prices very quickly.
So what? Maybe you disagree with the market. Well, that's a dangerous path for us small individual investors. The same way we can't pick which individual stocks will outperform better than chance, the same applies to countries. We work with limited information, emotions, and cognitive biases.
As a side note, it's worth noting that companies listed on US stock exchanges are not 100% reliant on doing business in the US. Most of them are multi-nationals selling globally, just like there are European-listed companies with US sales.
Rather than miss out on 63% of the global equity market, I would take my biases out of the equation and invest in countries in proportion to their market cap with a global equity fund like VT. In Canada, you might need to piece this together from multiple funds (and possibly consider possible the tax advantages of overweighting Canadian stocks), but using the same general principle.