Could it happen that a botnet would gain 51% of the hashing power?
20% seems like a big number to me already.
And that's why people need to get more miners online. And mining for either themselves or in a number of different pools.
Do you expect miners to mine unprofitably?
Well in the beginning BTC was worth nothing, but you could mine tons of them easily.
Now they are worth a lot more than 0.01 USD.
Some people are mine and hold.
Thinking of....maybe I need to think about one of those other slc/ltc/etc variants.....hmm...
If I ran a Bitcoin business I would hold 50% of all revenues and liquidate the other portion to pay off employees and restock inventory.