How often do good quality SSD's die. Hugely overblown concern like the nonsense a few years ago regarding swap ( I have a database with millions of entries on a mac server writing 24/7 and I am losing like 1-2% a year in terms of longevity, meaning my mac will be 50-100 years old by the time the SSD is worn out)and if your external drive goes dead, you're toast too ...
Only a good backup strategy keeps your data safe, regardless of internal or external storage
And thats heavy reading, writing and even swap usage (10-15 gb of swap)