And higher hashing power is more secure. The higher the hash rate the harder it is for anyone to pull off a coup of the blockchain.
This is not correct. If you hand mining over from a decentralized system of tens of thousands of GPU miners to one ASIC manufacturer it does not increase the network security.
For this reason we need to change the hashing algorithm from time-to-time, so that no ASIC can be produced (ASIC production takes a lot of time).
Honestly, it's just not worth it. In a few months, the same amount of time that it would take to find a new algorithm, if not longer, and implement it, Dash will be on Evolution. With Evolution, transactions will be approved by Masternode Quorums and the hash will only be used to randomly group these Masternodes into quorums. The miners will still include transactions into the blockchain, however, they will have no choice as to which transactions to include. They must only include locked transactions that passed a Masternode Quorum first. If they try to include anything else, it will be rejected by the Masternode network and the miner will lose the block.
It simply will become a new and infinitely more secure network soon enough. So please don't fret. Once this is in place, it won't matter if we only have one single miner.
I'm not sure this makes the network any more secure at all...in fact it could very well weaken it. There is still nothing to prevent somebody from creating a malicious masternode. In standard POW systems, you have to achieve some level of hashrate close to 50% to be able to do some significant damage. (its worth mentioning there is general misconception that you need 51% hash power but that simply guarantees the attack will succeed. You can successfully execute double spends with much less hash power than that).
As a typical POW network grows (i.e Bitcoin), the overall hashrate will grow. That means a major player wishing to disrupt Bitcoin has to spend more to pull off the attack. For example if the US government wanted to kill Bitcoin they might have to spend billions designing, manufacturing, and deploying enough asics rapidly to overtake the network. At a certain point (we might already be there) that becomes impossible. The amount of money they have to spend would be astronomical, and don't forget the network would continue to grow as they move toward deployment so maybe they get done and they still don't have enough hash power.
Now as for Masternodes....like I said earlier there is nothing to stop somebody from creating a "bad" masternode. So if you're a major player, like the US government, now all of a sudden you don't have to build and deploy any hardware at all. They can spend the same amount of money producing asics, but instead just buy Dash. Once they have enough, they set up their bad masternodes and start wrecking things. The Masternode system significantly reduces the amount effort it would take for a new player to overtake the network.
Some people might point out that there is a new masternode selection method that takes age into account. So what? A bad player isn't capable of bringing them online slowly? In fact it would actually make more sense that they take a little bit of time. If they accumulate Dash over time setting up masternodes as they go, everything looks fine. It could even be mistaken as a healthy network because the price will go up from the purchase of so much Dash and more nodes are going online which at first glance appear valid. At a certain point they just need to "flip the switch" on their bad masternodes and the network now belongs to them.
To take over bitcoin the "bad guy" only needs to take over 2 or 3 pools... so you where saying...?