Because programming languages are not the only thing I want to learn. In fact, I know that the time required to really learn all the things I'd like to learn far exceed my lifetime. So if I could learn about a bunch of them quickly and then decide on which ones to focus later on, that would be awesome.

In that case you're not "learning" though- more like "exploring". No?

>Why is everyone in such a rush?

because most people are desperate to get a job that provides them a decent standard of living

I agree, but the concern is that desperation is not a good guide. I appreciate that not everyone has the privilege of sitting comfortably for a few years immersing themselves in the knowledge of a deep subject, but I fear that without that the goal of earning a decent standard of living will not be quite achieved.

What I mean is that I've had programming jobs that didn't need a lot of deep knowledge on my part and they weren't jobs I wanted to keep. I wanted to keep the jobs where I was valued for knowledge and skills that I had worked hard to get. Those jobs gave me a decent standard of living, including the improvement to quality of life gained by the appreciation of one's value by one's colleagues, and the self-esteem and confidence that this provides.