Dangers of limited SSD longevity for heavy Lr users?

I don't have so much to offer technically as it has nearly all been said above.

I'm still a believer in a local RAID format drive or partition set or even better in off-site Cloud storage if your www speeds are fast enough.

Here in Australia many of us are just coming up to NBN connections with improved speeds (from in my case 5Mbs ADSL to 100Mbs coaxial.

Thats getting close to be comfortable for backup security at decent speeds . . .

SSDs do have a write limit, but as you're already doing, it's important to put that into perspective:

• Are you writing the volume of data that would run you right up to the limit? The articles I've seen talk about a cheap consumer SSD starting to fail after 300TB of writes. Is it likely that your work in Lightroom will write 300TB of temp files over, for example, a 5-year period? 300TB is equal to 5 TB per month. If your drive stats say you're not close to approaching that write volume, the write limit shouldn't be a concern because in the study I read, 300TB was for the worst performer, which was already well past its advertised limit. Every other drive lasted even longer.
• How often have you replaced drives in the past? For example, if there's a strong chance you're going to replace the SSD in less than 5 years (for more capacity, to upgrade to NVMe speed, etc.), then it's very unlikely that the write limit is going to get you before you decide it's time to put in a new drive anyway.
• In the unlikely event that you do hit the SSD limit (and it won't be for several years), what's the worst that can happen? A 1TB SSD is under $100 today, so the cost is not a major negative consequence, especially since that price only keeps dropping. Data loss should not be a problem if you're keeping backups.
• Is the SSD write limit the biggest problem here? Probably not. If you were to use a hard drive instead, now you're placing bets on which end of the reliability bell curve the mechanical hard drive will fall. In other words, it's not just a question of whether the SSD will hit a write limit. It's comparing the risk of SSD write limit failure to the chance an SSD will die due to another possible failure mode (heat-induced failure, manufacturing defect, power surge…) and to the expected reliability of a hard drive. Out of all those modes, SSD write limit is one of the least likely.
• Both SSDs and hard drives can fail at any time, so either way, the mantra is backups, backups, backups. As long as you keep to a rigorous backup routine, your eggs are not in one basket, and you don't need to worry about the failure of any individual drive. You should be prepared (backed up) for such a failure at all times, especially when running a business.
• Lightroom read/write volumes are probably nothing compared to what's written during, for example, HD video editing. But an SSD is standard in video editing configurations now because hard drives are just too slow for 4K+ editing and caching.

As long as it's easy and quick to replace the SSD in your next computer, and as long as you're keeping good backups, the SSD write limit risk is probably not significant. There are too many other reasons that you'd replace the SSD or hard drive before the SSD write limit becomes a factor.

DeMariaPhotography  wrote But my main question is:  With all the data writing that goes into (1) saving tens of thousands of raw files, and (2) working in Lr,

When you transfer thousands of raw files from camera card to computer, the nice thing is that each raw file only requires one write to store it. After that, nondestructive raw editors like Lightroom will not write to that file again. When you "edit" that raw file, what happens is that Lightroom makes a tiny update inside its database, which might only a few GB in total. The image file does get completely written out again at export, but if it's a JPEG, that's just a couple MB per file.

The major write volumes by Lightroom would be:

• The previews file
• The video cache
• The database (during automatic backups)

By file size, video editing might involve a larger volume of writes. But as far as the number of writes, the biggest offenders might just be the OS itself. It's constantly updating its virtual memory swap file and caches. (The cache folder on my system is over 15GB.) Either probably writes a lot more than Lightroom during the course of a day.