Why would you need to buy an SSD specifically for storing a text-document on it?

I wouldn't...I would put it on a flash drive.

And you're wrong about the benefits, doing operations such as searching for or replacing words or phrases in large text-files, or even using grep-commands in folders searching multiple text-files at once for certain words or phrases is several thousands of times faster on an SSD, and can easily take several seconds if not minutes on a normal hard drive depending on file-sizes.

You're wrong because you misunderstood what I was saying. I never said it wasn't faster. I even said specifically that it was. It's just that in this case it was a script for a game. How big do you expect that text file to get? Like I said, in this case, it will be faster, but just not "definitely worth it". The difference would be minuscule.

You're also wrong about if it was being served online to thousands of people at a single time. The biggest benefits of SSDs in this case is the reduced latency, and serving a text file to many people online isn't very dependent on latency unless you're giving some very specific service. And in that case the entirety of the file would be in the RAM and no operations would be done on the SSD/HDD anyway.

You're wrong and misunderstanding my comment. I'm not talking about consumer uses. I'm talking about a game script and an SSD, and why an SSD is not "definitely worth it" because worth implies purchasing one.

The biggest benefits of SSDs in this case is the reduced latency

Maybe for a consumer.

serving a text file to many people online isn't very dependent on latency unless you're giving some very specific service

Yeah...I never mentioned the low latency, I was talking about iops. Thousands of people connecting at once, try that on a 7200 rpm drive.