I've not sold any firearm that had not set unused for a couple of years. Of those I have sold, I did so almost always because of discomfort to shoulder it secondary to my many surgeries.
The only one I now regret selling also fell into the previous statement: a USA-made Weatherby Mark V (9-lug) .270 Winchester. I sold it believing I would never be able to shoot/hunt again. Then, I pulled off a major medical miracle. So, I lost my rifle, but regained my health. I'd call that a "fair" trade-off that I gladly can live with.
In the end, I got myself a Winchester M70 Super Grade .30-06, which I have wanted for nearly 30 years. Don' cha jus' love a happy endin'?!
Geno