SSD Prices

[king1]

Large SSD Capacity are not as common mechanical drives ( yet) 

You have to remember, (when it comes down to it)  an external Drive is nothing more than a Standard SSD or mechanical drive in a fancy case. Their size is still either 2.5 or 3.5" Drives inside the case, with the occasional M.2

These drives are still the same for failures as a Drive in a PC / Laptop. Saving all your data ONLY on an external drive is dangerous, and not safe from lose.

I don't get why using external HDs would be more dangerous than an internal one. At any given time my files are spread across 2, with a third used for backup. The backup gets locked away when full. Advantages are that I can lock all of them away when we go away (usually several weeks a year in the camper) so that a break-in might result in the computer getting nicked, but not my data. I also have flexibility to take them with me if I wish. I don't usually do that, rather do the reverse - when I download photos to the laptop I immediately back them up on to 2 portables, so that until I get home and put them into the main system I have three copies.

The only time I've ever had a problem was when windows warned me that something was amiss and I let it "fix" it, then realised that it did that by deleting a whole folder. So I just retired that drive by plugging in the next and copying through the files I needed, including the backup copy of the missing folder. Problem solved without having to mess with the main computer.

And the biggest reason of all is that the total of the working drives is way more than the space on my computer. I'm mindful that the desktop SSD has a limited life and am staring to think towards what comes next, but am not panicking yet.

external drives are easily knocked and dropped, lost (yes it happens)...  mechanical hdds are shock sensitive, a drop from 30cm onto the floor can kill it... SSDs are less prone to shock but cables, connections, sockets etc can still be damaged.

Most people tend to look after their laptops better... 

But it is good you have a backup, the rule of thumb is something like more than one copy on more than one backup medium...

and SSDs in laptops can usually be upgraded if you want more space, without reinstalling ...