Honestly I do not see why you need a system like the pi to program. Just fire up an environment, which you need to do on the pi anyway, and with the added benefit that your main computer does it faster.
I learned python with the IDLE environment at first, but it was quite sucky and frankly was even better to do it with notepad++ and add python as a third party compiler: https://docs.python.org/2/library/idle.html
And later Enthought Canopy: https://www.enthought.com/products/canopy/
Other languages have different environments that work quite well, say Eclipse is very good for Java. I use notepad++ for various things as well, and I've heard Microsoft Visual Studio is quite solid for C++, but I'm no programmer in that language, so someone may have better options.
Fucking up is hardly an issue, because you write code yourself so know exactly what it does.
And eih, ye, learning "how it works" is nothing more than installing an OS. Not hardly rocket science you didn't know. The raspberry pi is "just" a low-powered computer, but tiny and cheap, making it perfect for solutions outside the reach of a home computer, say an extra system to make your tv a "smart-tv", or 24/7 monitoring stuff without using a lot of power, for say domotics and surveillance, or a low-power webserver. Convoluted robotic experiments may make benefit of its tiny size.
The basis it was originally designed for, was giving a cheap solution to schools and development areas to indeed, learn to program and general IT, but with the thought in mind to keep it cheap because these places had no computers to begin with. You do.
But anyway, good job on taking matters in your own hands! It will for sure help you among your peers in getting further in life. - Which was actually exactly the purpose I got my raspberry pi for.