Why do we need distributed computing?

Question

Highload

Good day!
The question is purely theoretical.
I came across several articles where guys make clusters of raspberry pie. To the questions "why?" answers, approximately, such:
- because I can
- for educational purposes
Well, great. I especially like the comments like: "Such a system can be easily transferred from single-board devices to more serious computers and there will be generally top performance. Well, now there are no such tasks, but when they appear, there will be a ready-made infrastructure."
Gives me a little smirk.
Then I looked, there are projects in which you can connect your computer and there are some complex calculations, such as obtaining medicines, modeling for physics and space, and in this style. It seems like you are doing something useful, even giving some pennies (which usually do not pay for equipment and electricity). But many people slaughter with the thought "the computer has been thrashing for four years, and it is not clear what is being done, maybe the Americans are developing bacteriological weapons, and somehow it has become boring."
For mining, of course, it doesn’t roll.
So it became interesting, are there any tasks for distributed computing that can give at least some (albeit minimal) financial output? Well, or at least set some task for yourself, without these "space analyzes" here,