If 80% of delegates act differently from the wishes of stake holders, they can be voted out. So, I think the only major worry would be someone gaining 51% of the money supply and attacking. Even then, it would be a stupid waste of money, as you are killing something you own a majority in and spent a lot on to gain that stake.
If 60% of stakeholders decide something should be done differently.. Then that is there choice, no? The ones that don't agree can sell their stake and start a new chain on their own. That makes sense to me because Bitshares looks at cryptocurrencies as a business. If you own 51% of a business, you should be able to do as you please. It is like how a democracy would work or business would work in the real world.
Exactly, DPoS works like a representative democracy. Bitcoin doesn't but is designed anarchistic in nature where a majority of the community nodes, miners, or developers cannot force any user or miner with new changes they disagree with.
There is a reason I used the figures of 60% DPoS stakeholders and 80% of the delegates. Ever notice how in representative democracies, politicians will campaign on one platform and than have no obligation to fulfill their promises once elected. Nowadays you can almost guarantee they won't do what they promised and often the opposite. What guarantees do stakeholders have that their delegates will fulfill their promises and remain true in character? You say it would be counter-intuitive for any delegate to do anything to harm his investment but I just gave one example where a majority of delegates could decide upon something harmful that they would assume is beneficial: blacklisting.
With Bitcoin you always have a choice , down to the individual, and the miners and developers are held in check by a revolt(hard fork) that could happen at any moment something controversial is proposed. Not so with DPoS , because by design all users whether they vote or not are under the "social contract" of going along with the majority and after all you cannot undermine the vote as that would undermine DPoS in principle.
Bitcoin uses a representative democracy. Mining pools are the representatives and miners vote on those representatives with their hashing power. PoW and DPoS are not comparable to our current representative democracy, because they are completely liquid democratic systems, in so far as delegates and mining pools can lose their voting shares at any point and their task as a representative are easily understood and auditable by the public.
Your last point doesn't really make sense. You can hardfork a DPoS chain...