That's because they do experience intermolecular attractions and they don't have high velocities or high translational speeds. And that means these intermolecular attractions and low velocities will keep the molecules together. Now, of course, some of these guys will have enough kinetic energy to escape this environment, but that's a different idea. That's called evaporation. And when you evaporate from a liquid to a gas, the gas gains that high velocity escapes. And now it no longer experiences any intermolecular attractions.