They buy specialized feeders and baffles and any number of devices to keep the squirrels out. Squirrels are determined when food is involved, so solutions don't last very long.
My spouse, though, finds squirrels more entertaining than birds. So we bought a squirrel feeder. Far less varieties of those on the market. It's up on the patio wall, full of big corn kernels, seeds, and peanuts in the shell. Squirrels can eat food from the tray, or lift open the roof to reach inside.
And occasionally a bird flutters in to eat the seeds that hit the ground.