Have you considered the possibility that some of your people are unmotivated because you act like a jerk to them, and you're perpetuating the problem?

If you'll forgive me quoting my own post (https://news.ycombinator.com/item?id=9117035): A couple of jobs back, I met with a supervisor to proudly tell him that a gigantic, exhausting project I'd been working on for the last nine months was finally ready to deploy. His response, almost verbatim, was "Cool. Here's what I need you to do next..." I found it nearly impossible to care about what he wanted for the rest of my time there. 60 seconds' worth of interest and congratulations would have gotten dozens of hours of extra productivity out of me.

If you read the article, the author is talking about his relationship with coworkers, so I'm going to assume we are talking about one's relationship with coworkers. That being the case, I certainly hope you don't think any of your coworkers are "useless."

You don't have to be kind; you don't have to be anything. On the other hand, if you want to be a good engineer, with goodness defined as how much one contributes to the team/company, then you probably should be kind. If you feel like your teammate is unmotivated then it seems like if you want to be a good engineer you would do your best to motivate that person.

Having an uncaring attitude towards your coworkers could well lower their motivation which would mean your net contribution to the team is lessened as well.

"I still have little use for useless people"

The trouble with this is that you could be wrong. They might be "useless" to you but not the rest of the world.

Yes you are right, you don't have to be kind, but kind people are advancing in their carrier faster. If you want to play this purely based on logic, and you want to advance in your carrier than you have to be kind. :)

I empathize with you. But be careful, the trouble is that those people fill their time at work with political games. They are dangerous to someone who wants to be head down doing great work.

The problem with useful/useless is how often you have to re-run the function with people you see more than once.

Run it only once, and perma-store the info? Their state could change and you miss out on opportunities.

Run it each time and behave accordingly? That doesn't work, either. People know when they're being used.

Honestly, being kind all the time sounds like a lot less work.

It depends on how they are useless. If they put genuine effort into trying not to be useless, I will still be kind to them.