From my very (admittedly very inexperienced) perspective, both views here are valid: it's foolish to scour the world for nails, but it doesn't hurt to make a hammer.
Build the technology, think of how it could help, and if you can't find a niche in the world that it fits, don't force the issue. Move onto new things: perhaps re-use some old ideas, of course, but actively get a wider experience, so that you increase your surface area of finding some way for your technology to help.
I have no idea what blockchain does or not. But just because its applications have turned out to be scammy, is it possible that it still has good uses in the future?
May be and may be not. OP is saying more generally that we should stop looking at tech that has no uses. I am disagreeing with that stance and it is just silly to be so wound up about Blockchain zeitgeist to not see through the fog.
the problem with Blockchain is that it is strictly less efficient than centralized databases. therefore the only reason to use it is if you can't trust a centralized database. it's like torrents in the alternate universe where torrents were slower than a download from a server.
It's not a bad analogy. Torrents have more cumbersome UX and are less data efficients than direct downloads, yet they are widely used for some types of applications.
This is waste to keep throwing resources at something because maybe someday something good will come out of it.
There’s many more areas like sequencing genomes and fighting cancer that these programmers could be spending their time on.
Build the technology, think of how it could help, and if you can't find a niche in the world that it fits, don't force the issue. Move onto new things: perhaps re-use some old ideas, of course, but actively get a wider experience, so that you increase your surface area of finding some way for your technology to help.