If the choice of a travel companion is considered the only factor, then a crucial step in planning is missed. A decision sequence would rather be: if I have a budget of €500, then I first choose my destination, then find companions with the same budget, otherwise I travel alone.
The available budget is often the real starting point, not the desires of a group, especially if you're aiming for a weekend for €100 in Amsterdam.
If the group insists on a more expensive destination, then the discussion should focus on funding, not desire.
Otherwise, the influence of companions is just one variable among others, not a universal rule.