Engineers with 5 YOE are making $500k+ a year at these companies because they are generating much more than that in revenues and profits for the companies. Airbnb is worth $110B.
It's not all blinking cursors, there are thousands of little experiments going on all the time. Increasing the number of bookings by 2% here, 3% there. Increasing the average price of bookings. Random extra features here and there to close that one whale of a client. Expanding into corporate accounts. Improving performance by 5% to take a big chunk out of the tens of millions of dollars infrastructure bill.
From a 10,000 foot view looking at the product, it always looks like it's 90% done in the first couple of years and then things just coast along lazily. But from a profit point of view, that last 10% can generate hugely outsized returns. It's the power of exponential growth, all those extra late nights and tiny improvements that move the needle just a little bit all compound over time.