Also, it's really heavy (I'd say at least over 1kg), so by the time I sold it at less than the current price because it's no longer new (also mine is 1-4A, the current edition is 1-4B) and paid postage to package and ship it somewhere, it's probably not really worth the effort.
For example if you are interested in large integer arithmetic the 2nd edition of Volume 2 has some exercises that develop some methods that, if I recall correctly, I found more suited to my needs than the methods in the text when I was working on a large integer library.
The 3rd edition dropped those. I've long forgotten most of what I learned when working on my large integer library, but if I had to learn that subject again I'd probably actually start with the 2nd edition, and then check the 3rd edition to add to that.
You should imagine that you are forced to sell it every day. Eventually you'll either sell it (or donate it (your local library might appreciate it)) or start reading it.
Semi-serious question: Which of the following do you mean:
A. Every day, you should imagine that you are forced to sell it; or
B. You should imagine that you will, every day, be forced to sell it.
(I teach law students to spot and fix ambiguities in draft contracts; this would be a nice practice example :-) )
OP imagines that there is a point in the future where they read the book without commiting to it. Selling/donating it would put an end to that possibility and force OP to imagine a future where they cannot read it, and hopefully helps them assessing one va the other, and prioritizing accordingly.
https://about.usps.com/notices/not121/not121_tech.htm
I've used it to buy/sell large tomes like this and it is really cheap ship things this way. It's not the speediest of delivery methods.