The Mate would really like to know. There are probably a few other people who think I'm nuts. They might not be wrong.
It comes to this: curiosity; stubbornness; solidarity; convenience; that car accident; environment.
The service industries have a whole raft of employees whose job it is
to keep moving, whatever the weather. People who are largely invisible
to the middle class except when they make headlines by biking on
sidewalks or the wrong way in traffic. I ride in solidarity.
I biked to the train to get to work yesterday in the beginning of the snowstorm, and discovered my bike handles pretty well in just a couple of inches of fluffy stuff. In the middle of the snowstorm on the way home, I discovered my bike doesn't handle so well in four inches of snow that's been driven in. Also, the derailleur freezes and doesn't work so well. I pushed my bike where I had to, I rode it where I could; I made it home.
I grew up in New Hampshire, and played and skied and snow-shoed and walked in conditions considerably colder than what New Yorkers consider reasonable. I'm also aware that people live in far colder climates. The saying is, there's no bad weather, only bad clothes, and there's a fair amount of truth in that. People typically own clothing appropriate to their own climate, so dressing for significantly colder temperatures can be a little complicated. Lots of layers is a good start.
I biked to my physical therapy appointment this morning because it's the quickest way to get there. Public transit takes at least an hour; I could walk the distance in somewhat under an hour. Plus, curiosity again. Turns out bike lanes were plowed but not salted, and blocked by the usual obstacles such as parked trucks. Also, people were shoveling snow into them off the sidewalk (plowed and salted) and their parked cars (buried).
Plus, after an "accident"* in which my car was nearly totaled by a runaway truck, I still have a phobia about getting in a car, any car. (I also still have chronic pain, weakness, limited range of movement. Hence the above-mentioned PT.) If I can avoid it by taking my bike and/or public transit, I'll almost always choose that option.
Finally, the environment. Riding my bike and taking mass transit require far less fuel than driving a car. I'm committed to doing what I can to reverse climate change. On my own, it's not much. Biking in all kinds of crazy weather gets people's attention and, I hope, gets them thinking, "I can do that too!" (I would recommend that anyone who hasn't been biking regularly wait until April.)
Even I have my limits, however. I'll be driving to my 4:30 class this afternoon. And I'm grateful I have the option.
*The NYPD has recently started using the word "collision" instead of "accident," in recognition of the fact that at least one of the drivers screwed up almost every time.