What will happen to the plane if the co-pilot is not sticking to him checklist? It will result in an accident. A plane requires both pilots to stick to their task. What will happen if the crew will not serve their passengers with love and care? There will be an uproar. What will happen if in a long distant flight inhouse entertainment breaks down? The guests will not be happy.
Now replace co-pilots with founders, the crew with team members, and in-house entertainment with the product. The smooth functioning of a startup requires it all to work as an orchestra. Any single piece not performing as desired can create havoc. It can derail the entire startup.
So running and aircraft and a startup are the same. One mistake and life of the crew, members, and well-wishers all goes to dump. Hence the most important part is picking a co-pilot and then the crew members.