Astronomical telescopes are now mega projects and cost $1Bn and although they are pitched to solve the current interest of the day they are general purpose machines and with upgrades and new instruments have a life of perhaps 50years.
It seems that large accelerator projects are built to answer one question, to find one particle. But since the design must be based around the particle having a particular energy and the cost and timescale being so large - you have to be pretty damn sure that you expect the particle to exist and at the predicted energy. It almost seems that if you had a good enough estimate to build the accelerator then you don't really need to!
Is something like the LHC a one trick pony? You turn it on and confirm the Higgs or if not - build a bigger one?
Is the LHC really a more general purpose experiment but the Higgs gets the press attention or is it just that the nature of discover in HEP is different and you need to build a single one shot experiment?