Yes, but it's a lot easier when you're young and have the energy for it. Basically, you have to spend a lot of time staring at the monitor, often trying to figure out other people's code, unless you're coding everything by yourself.
Depends on your definition of junior programmer. My definition of a junior programmer is one with a computer science degree, or equivalent experience, who can get an entry level position in the industry. I still wouldn't hire him to implement my strategies. Can someone do functional programming, maybe with scripting languages like Python, - sure. But I would not trust that level of skill to do anything complicated. I am not saying this because I have a computer degree - I do not. I am self taught. I had a mentor who helped me learn object oriented programming using C++ and he hired me trusting in his knowledge of my talent, not my skill. It still took me about 2 years to get competent. I am not discouraging anyone from going down this road. The OP says he is 30 years old, so it is really doable. I am just providing my background for reference.
Actually, I'm 62, will be 63 next month. My first coding adventure was on a CDC mainframe in Fortran and later Compass assembler. Then on to Pascal, C, and later C++ and some Java and C#.
Do you apply your programming knowledge in your trading? I use C# for all my web scraping data analytical tools. I really like Microsoft's VS Community IDE, and the more recent VS Code IDE. Their new "minimap" code scrolling feature is just delightful.
I've written a ton of strategies in C# for NT, none very profitable afaik. It seems to me that coding is the easy part, finding a profitable strategy is the hard part.
Agreed. Junior-level or beginner coding is pretty straight-forward ... obviously complex software development takes a little more experience Finding a profitable strategy ... or a set of profitable trading strategies ... that's usable for more than a short period of time ... is like the goose that laid the golden egg