Startups are inherently risky. Period. Nothing can be done to address that. In markets that are primed for disruption, and the startups that go a-hunting, execution is the most critical variable. I've seen crappy plans executed well, and succeed, over excellent plans executed poorly. The primary risk is that the team assembled will fail to execute.
How does management/leadership/funders/etc address this inherent risk? They start by requesting a plan, a strategy, of what you are going to do and how you are going to do it. This forces the entrepreneurs to thoroughly articulate their plans and assumptions, and is a healthy exercise that requires that operational leadership think through all the branches and twigs of the startup decision-tree. I've seen people change their startup idea 180 degrees once they started thinking it all the way through, usually when forced to write the strategy or business plan.
Having said all of the above: It's a great thing to read once, argue over, and then use as a doorstop.
Battles are won on the battlefield. You can plan, but execution of the plan, and adapting of the plan, is ultimately more-important. This is why successful armies over history prevailed over numerically superior enemies, adaptation. The General would have a framework of what they wanted to accomplish, the strategy, and array the resources at his disposal on the field of combat to best execute this strategy. Once deployed, and battle enjoined, then successful armies had degrees of latitude on how their combinant parts were able to perform their role in the broader strategy. They marched around clumps of trees, they changed their rate of speed to confound archers, etc.. They had unit-level operational autonomy.
Viewed from afar, it may look like utter chaos, but each tactical unit knows that it has a role to play ('capture that hill', 'flank the flankers') in support of the broader strategy. You are still executing to the broader strategic goal, but you are intelligently adapting to the situation on the ground to achieve it. Think about the movies you have seen of soldiers marching shoulder to shoulder into awaiting cannon/rifle fire, because that's how they were lined up. They fail, because they fail to adapt.
This is a big issue for many entrepreneurs, because they have an almost religious zeal for their idea, their 'baby', and are loathe to turn it over, even in part, to other people to execute. They fear of losing control of their idea, their position in the capitalization table, their board of directors, whatever. They cling to a command-and-control structure that requires that everything go through them. Ultimately, the startup, whose advantages lie in it's ability swiftly proceed where larger incumbents are unable or unwilling to do so, gradually slows down to the rate of speed of the incumbents or competitors. They lose their strategic advantage. They then proceed to get the hell stomped out of them by the (typically) numerically superior enemy. Either the leadership delegates operational autonomy to the component parts, while holding the reins of strategy, or the organization calcifies.
This can also be an issue for startups that answer to external parties. The startup is on-the-ground, adapting in real-time to new threats and variables on the battle field. (This doesn't extend to those startups who are randomly running around without a compass and confusing activity with progress or strategy). It's nigh impossible to communicate all of these adaptations to an outside observer, and that they are steps on the path towards the ultimate objective. Even the completely rational traditional venture funding mechanism, that funding tranches are tied to performance metrics and gates, will cause your strategy to suddenly become less malleable and more rigid and restrictive to the operational realities. Anything that hinders your ability to adapt will reduce your already abysmal odds of success to even lower percentages.
It's not impossible to communicate the complexities of battle once enjoined, but it is tricky as hell. It requires patience on both sides, and the acceptance of both parties that you'll need to meet half-way between your respective worlds. The really good Silicon Valley and Boston VCs have this part down pat. They have deep domain expertise, operational backgrounds, extensive networks, and (above all) the ability to say 'I don't know anything about that, tell me more'.
The magic is in balancing strategic objectives with tactical adaptation, while over-communicating both to your constituent investors to assure them that you are not boldly charging ahead with an outdated, obsolete, or ineffective plan after receiving valuable market feedback (which can be simply reduced to: "they bought" or "they didn't buy"). It takes considerable time away from running the business to over-communicate, so the best thing you can do at the time of funding is agree on the communication channels, individuals, and intervals. You then build this into your daily/weekly/monthly workflow, and proactively keep investors informed and up to speed without onerous time-tax on your already exhausting schedule.