4. It's not in the interest of a botnet operator to do a 51% attack because that will make his booty worthless. Unless he gets paid by someone whose aim it is to destroy bitcoin. But that someone could just do the 51% attack himself without going through a middleman.
You don't know how to do a proper 51% attack...
For traditional bitcoin type chains:
1. Aquire at least 51% of network power.
2. Aquire coins (preferrably through mining but could be bought).
3. Start private chain fork.
4. Sell your coins on the current public fork of chain.
5. Get your $$$ out of exchange.
6. Publish your private fork of the chain.
7. If any exchange remains open, goto step 3.
You make your money at least once, exchanges quickly go bankrupt, and you have the evil mastermind satisfaction of destroying a chain.
Once that chain is dead, you move onto the next one.