A very good question! ("Would you write code for free?")

Especially, if it is asked by someone from the States :)

When reading more I found subtle hint about selling, about your selling. But it is somewhat subtle, so I will write an answer, even if I am not your target.

The answer is yes! Or maybe no, if one considers future developments.

While I have written a lot of software when I was not a programmer, there were times when programming was just fun.

First of all: programming was not in my education. I have studied electronic engineering at the Technical University of Vienna.
So what did I do in the beginning? I have designed and built hardware. The first two projects that I did with microprocessors were measurement devices. (256 Byte RAM, 2 kB PROM, Z80) So what was measured) One instrument measured environmental data in 1974 and the device had to run without human interaction for at least one year. The other device was measuring temperature in the range of 1 to 1600° Celsius with an accuracy of 1°. It was the successor of an instrument that used a resistor network for simulation of a polynom of 4th degree. Calibration had needed more than one days work. My instrument needed one measurement run of half a day, measurements were taken all hours. The calibration needed 2 minutes. Setting of 5 twenty gear potentiometers.

I changed companies and was dealing with image analysis. I did not do real programming, maybe you could call it application programming, but I did not consider it programming. It was just applying some software tools.

Any free programming at that time? Not really. But analyzing software I did. During our honeymoon trip to Lake Garda in Italy I took some software listings with me. They were describing the software of the DEC PDP-11. After lunch, when it was too hot to do anything else, my wife rested and I studied the floating point software simulation of the PDP-11.
It was great. I had only a dissassembled listing and had to find out, what could have been symbols and how was the structure of the subroutines. Addressing data of subroutines in the memory in the particular DEC way would not be allowed today :)

Actually I did programming, too but that was because I was employed by the university.

I skip a few years. Eventually I programmed another measurement device where I had to do everything from scratch, including adapting a specific operation system so it was multi-processors capable. Then came a time when I was selling pianos. No programming, just supervising what somebody else programmed in his spare time.

And then in the 90s, I found the successor of FORTH. I had found SMALLTALK. Without any idea of applying for a job as programmer, I invested 30.000 ATS, would be 6000 € nowadays to buy myself the development system Visual Age Version 3 from IBM. My computers were much too small to handle it. Sometimes I had to wait 20 seconds after I had selected something from the menu. But I had been fascinated. The first thing I programmed with it was a "game of life". Actually, I wanted to enhance it to get a simulation of interacting cells with particular properties. Would be still interesting to do that today with the machines available today.
(When I write this I almost think of getting started with it again. Instead I have done some courses in machine learning and artificial intelligence. That satisfies me nowadays next to working through the bible of quantum computing by Nielsen.)

So here I was doing programming for "free". I had no idea to make money with it. I wanted to create "living entities" to program a higher version of "life".

As it turned out, I got an offer by a large company that was searching for Smalltalk programmers. Since I did not earn much money at that time I appied for the job. I passed the exam but I was not hired. Some problem with budgeting they had at that time.
They hired me however one week later and I stayed in the company for ten years. But it was not programming anymore. It was software testing. And I did that for the oncoming 20 years. In the beginning I was really testing, but that meant setting up a framework for automated testing. There did not exist tools like today. I had to program my own, but that was paid.
And then I programmed something for myself. It was a database for testcases. Very common nowadays, but not in 1999. Testcases were parameterized in Excel tables. Reworking on testcases was time consuming. My system is still used 25 years later.
I did it in my free time. My boss at that time smiled about my efforts but he did not believe in my idea how the system would work. One year later, when my system worked and was used heavily by the team which I led, he once came to me and excused himself. He was really surprised how it worked and how useful it proved for the company.
I did not get money for my programming.

But no! I did. Ten years later, when I left the company they paid me aroung 100.000 € for the right to continue to use it. I could prove that I had programmed it outside the company, outside of working hours. I had programmed it, because it allowed me to monitor the progress of testing projects. So I did it for myself basically.

Maybe, I will restart my "life"-project some time. Today I spend most of my time practicing piano, 3-4 hours a day, and writing a book about artificial intelligence.

So, if you have read so far, here is the facit: maybe I did not get paid for everything what I programmed. But you will never know if something pays off at a later time. Programming is fun! And it is LEARNING! and training your brain. Learning will always pay off.

Cheers
Hans

P.S: You can use my answer if you want it and if it suits you. But let me know if you publish anything of it. It is not money what interests me, just knowledge :)