ELI5: What engineering limits prevent us from building skyscrapers much taller than the Burj Khalifa?

We do not build skyscrapers much taller than the Burj Khalifa because the wind, the ground, and simple daily needs make going higher too difficult and expensive.

Think of building a mega-tall tower like building with toy blocks on a soft carpet, but with giant fans blowing at you.

Several everyday challenges stop us from going higher:

• Fierce wind: When you stick your hand out of a car window on the highway, you feel the air pushing hard. High in the sky, wind is so powerful it can push a building side to side. Engineers have to give skyscrapers special, twisting shapes or add giant pendulums inside that swing to keep the building steady, just like holding your arms out wide so you do not tip over on a windy day.
• Soft dirt and squishing weight: If you step on mud wearing high heels, you sink, but if you wear flat snowshoes, you stay on top. A skyscraper is unimaginably heavy. To keep it from sinking or tilting like a tree in soft dirt, builders need solid bedrock and massive deep foundations. If the ground is not rock-solid, it cannot carry the weight.
• The elevator traffic jam: Imagine if your school or office building was so tall that riding the elevator took twenty minutes. Cables holding elevators get too heavy to lift themselves after a certain length. To move thousands of people up and down, you need dozens of elevator shafts. Eventually, the building becomes mostly empty holes for elevators instead of rooms for people to live or work in.
• Water pressure and plumbing: Think of squeezing a garden hose to shoot water up into a treehouse. Water is heavy, and pushing it straight up into the clouds requires enormous pressure. Without massive relay pump stations spread throughout the tower, pipes would burst at the bottom or faucets would only trickle at the top.