(I say “have a tendency to rise” and “have a tendency to fall” because of course there are many other things which have an influence on prices, including changes in international prices, changes in government charging policy, changes in tariff policies, and similar factors.)
However, the question of whether or not private investors deem an investment project to be sensible very much depends on the future economic prospects of the euro area and Europe. And nobody would deny that uncertainty is rife in this regard at the moment – the “Brexit” risk is just one source of uncertainty.