However it may sound: It's good that this happened. People needs to be aware that 51% attack is a serious threat. It's great that the attacker gave the money back but it might not be the case for the other ones that are coming. We may even expect "companies" that offer "stress-tests" of cryptocurrencies actually doing 51-attack-as-a-service business in the future. That is why we need much safer solutions. Not only obvious fork-checking of every crypto on all exchanges which easy to do and nobody knows why still not all exchanges have it. We need more secure blockchains in general which don't run on the rules we have most common today. Some crypto's developing teams took effort already to invent something new. In fact steem is already a little different, as well as NEO with it's vote-for-a-miner strategy but both of them are centralised to much for now. IOTA has very different approach, very promising, but still people doesn't seem to be much interested in it. What people care is when to buy which crypto on exchange and when to sell it. What they don't understand is that crypto may be a way more than just a speculation tool.