Bert Wagner shows us a good way of converting strings to numbers when multiple cultures are in play:
Why are the salaries stored as nvarchar and formatted with commas, spaces, and periods?
Great question! Someone wanted to make sure these amounts would look good in the UI so storing the formatted values in the database would be the way to go…
Pretty for the UI, not really great for needing to do analysis on.
Admittedly, TRY_PARSE is slow, but for a one-time conversion as you try to fix a bad idea, it’s fine.