Does ice ever break in Netrunner?
Are you remembering to pay the extra 1C per existing ice on a server when you install? If you install the 3rd ice, you have to pay 2C installation costs as well as the rez cost to then rez that ice.

There are also many cards which the runner has which can derez or trash ice once it is installed, Parasite being the most used example from the Core set.

The runner also doesn't have to get through every time; if they sit there gaining cash the corp won't be able to keep them out indefinitely. This means a rich runner puts the corp under a lot of pressure, since if the corp tries to score an Agenda, the runner can break into the remote server. If the corp doesn't try to score, they will soon have an HQ full of agendas which will be very profitable for the runner to run against.