Mismatches between forecasted and actual costs and traffic figures are common in transport investments, especially in large scale ones, and so are delusions on future demand. High-speed rail project 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 delusion of success, namely Italian and Spanish HSR programmes. The Italian one shows excellent demand performances, but is among the continental worst cases for construction costs. The Spanish one, recognised worldwide as one of the most successful cases, is the one where potential demand estimations was systematically neglected and the planned network appears largely out-of-scale compared to actual traffic. The two cases show that the core of the problem does not lay in the wrong estimations of costs and demand, but on deliberate choices of overinvestment, overdesign and overquality.