I agree. I own all my books, no debt involved. Higher chance of profit if you can hold the af15 for at least 6-12 months and then flip it.
Well, if the book goes up, then that means your percentage profit would have been substantially higher if you funded the purchase with some debt.
The power of leverage as you would benefited from the entire increase in value while only having to pay a portion of the cost. Of course, it only works if you sell the book as opposed to keeping it in your collection long-term.
I think folks that debt finance for advantageous reasons are possibly ok (as in they could buy outright, but opp costs of existing cash exceeds the cost of the debt)...
however, as a general rule, if the average person is trying to fund comic(s) with debt because they don't have the liquidity to purchase outright, imo, is generally a bad idea and potentially dangerous path to go down