Blu-ray vs. everything else for data storage
It is interesting that this isn't cheaper.
I recently just did a massive data transfer where I finally moved all the data I had backed up from DVD to flash media. SSD, specifically. Why not Blu-ray? In both the short and long term, it's just not a good option.
Any Blu-ray burner drive (internal or external) will at the time I write this in January '23 run you 65 bucks minimum.
For blank media, you have two options. Regular and M-DISC. The M-DISC format is specifically for archival purposes and will outlive you regardless of what age you are. I'm not kidding.
When you do the math, regular BD-R costs about 88 cents per disc that can hold 25GB each. That sounds nice at first until you realize it takes 40 discs to reach 1TB of storage.
Okay, you say, I'll get 50GB Blu-ray discs. Now the price just doubled, and it still takes 20 discs to get 1TB of storage.
If I go with SanDisk 512GB USB 3.0 stick instead, that's a one-time $40 cost, and all of the 512GB is available immediately on one stick.
If I get a 3.5" HDD enclosure (about $30) and a 5400RPM 4TB HDD (about $65), the cost is $95 - but - I'm getting a full 4TB all up front, all at once. Yes, it requires a powered enclosure, but still, we're talking 4TB here. I could even go 8TB 5400RPM HDD if I wanted.
Blu-ray would be better if...
...the drives and media were cheaper. But they're not. And there's no good reason why they're not.
A Blu-ray burner drive at this point should be 30 bucks, but it's more than double that.
A 50-pack of BD-R DL discs (the 50GB kind) should also be 30 bucks, but it's well more than double that. And bear in mind I'm talking about regular Blu-ray and not the highfalutin M-DISC stuff.
The real kicker...
...is there is no guarantee there will be any new Blu-ray drives available even in as little as 10 years from now.
With HDDs and flash media sticks, I'm fairly certain there will still be USB A style ports around in the future. If not, there will at least be adapters available.
With Blu-ray however, yes the drive will connect via USB most likely. But if there are no new drives to, you know, spin the disc to read the data, that's a problem. If you decided to use Blu-ray today, the best long term solution is to buy an external drive, test it once to make sure it works, then put it in storage and hope it works 10 years later... which is not a good solution at all.
If Blu-ray were cheap, then sure, you could buy backup optical drives and it wouldn't be much of an issue. But again, it's not cheap.
You're just better off with flash media or HDDs for big storage.