Even if you magically knew which startups could be viable 8 years down the road, there's tons of factors completely outside your control that could tank a startup in an instant; e.g. covid, a world war, regulation, etc.
That "carpool as a service" startup might have had a great business strategy up until a pandemic showed up. And if you're spending 8-10 years waiting for a payoff, you only get ~3 shots to pick correctly.
