Try building a road system with just road workers, and no civil engineers or systems and operations analysts, and all this entails.

Or pay the house painter what you pay a software engineer, and see how many people paint their house themselves, or with less frequency. House painters would be priced out of the market, and more homeowners would fall, and/or have crappier paint jobs.

That is supply and demand in a nutshell, and how markets value a skill or talent you have to offer with obvious exceptions.