Because this only happens once the IOU has been put in circulation. In my example, the paper money I created was not put in circulation, consequently no redistribution effect took place. The analogy is solid and appropriate.
Ok, so what would be involved in putting it into circulation? In your original analogy, you simply you said you wrote an IOU. Unless putting it into circulation is trivial, then your analogy is neither solid nor appropriate. A substantial amount of work goes into providing a stable currency.
Just being perfectly honest here, I think your position has been shown to be logically inconsistent in multiple ways.
1. We started this discussion by talking about whether or not investment in BlockFi represented a destruction of capital. You said it didn't because money invested is not capital. You then later admitted that there are definitions of capital that include money. I would consider this an uncharitable reading of the initial point regarding investment in BlockFi. If there is a valid definition of the word "capital" in which the original point is true, that it is charitable to assume that was the intended definition.
2. You agree that burning money in your bank account would make you less wealthy, but somehow disagree that you cannot consider this destroying your wealth. That's inconsistent.
3. The "car IOU" analogy has an obvious flaw in that burning it does not reduce your wealth as was the case in the burning money example. Despite this absolutely crucial difference, you maintain it is somehow valid without an explanation of the difference.
You put the IOU in circulation by selling it or by giving it away. (I don't know what's so hard about that.) The point is that the act of writing the IOU doesn't create any new cars. And likewise the act of destroying the IOU, at any point in time, and regardless who's holding it, doesn't destroy any cars either. This simple example shows that no actual resources (i.e. capital) are destroyed as a consequence of IOUs being destroyed. If you still don't understand why this is the case, I don't know what else to say to you.