Mismatches between forecasted and actual costs and traffic figures are common in transport investments, especially in large scale ones, and so are delusions of the future demand. High-speed rail projects are often among the worst practices for cost overruns and demand overestimation, even where traffic figures may tell a history of apparent success. In the paper, we analyse two significant cases of delusions of success, namely the Italian and Spanish HSR programmes. The Italian one shows excellent demand performances, but is among the continent's worst cases for construction costs. The Spanish one, recognised worldwide as one of the most successful outcomes of HS policy, is the one where potential demand estimations were systematically neglected, and the planned network appears largely out-of-scale compared to actual traffic. In both cases, the forecasts were not simply biased, as well-known literature on megaproject failures has clearly shown: Italian lines were deliberately designed to increase the cost, and the Spanish network was deliberately planned out-of-scale. By means of the two cases, the paper will show that the core of the problem does not lie in the wrong estimations, but in deliberate choices of overinvestment, overdesign and overquality.