This is an experiment, where these NFTs allow you to receive my books for free, while potentially making a profit. Here's how it works :
You purchase one of these NFTs for some price P.
The hidden content contains a one-time-use coupon code for the book
You go to the link to the book's purchase page and, using the code, purchase the book for free. The image of the book should correspond to the image in the NFT.
If in the above step the code didn't work, then a previous purchaser of the NFT claimed the book. in that case :
you send me an email at email@example.com which includes :
the one-time-use code that failed (from step 2),
your wallet address
i receive the email and look in the block explorer for the NFT associated with the one-time-use code
i verify that the last purchase of the NFT is your wallet address (from step 4.1.b) and that i have not yet received any other email claiming the combination of data in 4.1.a and 4.1.b
i generate a new one-time-use code and email it to you, which means that both sending and receiving emails in step 4.1 should be valid
you check your email and your spam folder for my email and then use the new code to buy the book for free. note that i plan to do this manually and have other commitments, so there may be a few days' delay for me to get back to you, but hopefully it will only be a few hours.
You resell the NFT as-is for price 1.12 times P, plus your profit. So if P is .003 eth, your first calculation is 1.12 times .003, or .00336 eth. The .12 exists because you want to include my 10 % royalty in the resell price along with the 2 % fee that OpenSea will take, thus allowing you to receive 1.00 times P. Now, to make your profit, you would add whatever percentage you would want for yourself to the resell price - so say you want a 10 % return - you would add (0.1 X P) to the .00336 eth, so that in this example you would add (0.1 X .003) to .00336, which is (.0003) plus .00336, which would be .00366 for your final resell price. That's the same as multiplying the original price P by 1.22. if you can resell for that, you will have gotten a 10 % return on your NFT purchase as well as a free book.
note that if you resell the NFT in step 5 for a price multiple very much higher than 1.12, you will make a larger profit, as well as get the free book - but it may make it harder to resell it, as the person you sell it to will therefore have a higher P purchase price than you did, and if it is too much higher he may not have the capital. remember that the person who purchases the book from you will be planning to repeat the 5 steps above himself, to repeat the cycle and get his own small profit for receiving a free book.
The risk you are taking is that you will not be able to resell the NFT in step 5. So you should consider how likely it is that another purchaser will be enticed to receive one of my books for free while potentially making a profit, given the resell price you set.
Note that if you want to verify that firstname.lastname@example.org is a valid email, write an email which asks me a question and send it BEFORE buying the NFT, and i will reply with an answer. the same restriction mentioned above in 4.5 applies here as well.
The risk i take is some sort of cheating on your side (i.e. giving away the code in step 2), which is why i perform steps 4.2 through 4.4 above.
what you get : a free book, plus a possible small profit
what i get : royalty from the resell, plus an increase in sales of my book, which smashwords sends to publishing houses for the purpose of ranking them.