I’ve read Democracy: The God That Failed. I recommend you do too. It’ll give you a better grasp of the actual argument being made and you may find end up finding it more plausible. I only suggest this because your summary of Hoppe’s position seems to mischaracterize him as saying that any and all situations involving a non-owner/caretaker of a piece of property with a term limit must necessarily lead to short-sightedness, which is of course absurd and naturally leads to absurd conclusions like the one you drew.
Hoppe is really just making a “tragedy of the commons” analogy. A commons is a resource that is scarce (there are competing, mutually exclusive uses to which it can be put at any given time), but no ownership rules exist regarding it - if I want to put the resource (say, a pool) to a certain use (e.g. swimming), I cannot exclude anyone who wants to put it to a different use (e.g. industrial pollution).
The incentive structure is such that no one can take care of the resource in accordance with a fixed set of principles. (The pool, to be suitable for swimming, must be maintained, cleaned, etc., but I can’t do any of that if someone else is polluting it indiscriminately.) On the free market, we would expect that its capital value would tend to decline.
Hoppe defines democracy as basically that, as free entry into the helm of the ship of state, where no individual or group has the exclusive right of direction over who gets to steer.
(Naturally, real-world democracies don’t fit that definition perfectly - democracies have some rules about who gets to be president, about what constitutes a legitimate election, etc., on the basis of which anyone who doesn’t follow them can be booted out - but I think it’s fair to say they are closer to Hoppe’s definition than are other forms of government, say monarchies, which typically involve an ownership arrangement where the kingdom is counted as part of the ruler’s personal estate.)
It should be clear that Hoppe is not saying because democratic rulers are caretakers with limited terms, they must be short-sighted - or if he does say that, he shouldn’t because that would be completely baseless and would undermine his whole case (in addition to being irrelevant to his argument). Just because ownership of a resource is separated from posession or care or whatever doesn’t make it a commons. I can let someone else wash my car or clean my house or use my credit card while retaining ownership of the relevant property - the point is that no one gets to do anything with the property except on my terms; the resource is still owned. This is why your analogy to corporations is flawed. The corporation isn’t a commons because the shareholders own it and, at least in principle, the management is only there on their terms.
(Real-world corporations, of course, do plenty of evil things, not because of anything in principle wrong with incorporation, but rather because of various state privileges that have been granted to them which allow them to escape market checks on their behaviour.)
The rest of your comments, as far as I can see, are the sort of crude Marxoid generalizations about greedy capitalism people interested in honest debate ought to know better than to make.