Is anyone running the MN from a raspberry pi? Won't it get eventually overharmed for being turned on 24/7?

Yes, it was ASIC resistance.  Even from the very beginning Evan said he was hoping for 2 years without ASICs and strangely enough, that just what he got.  This is because the network needed to be strong enough for the change over, which it is.  This was not unforeseen.  

ASICs do strengthen the security of the network.  They do this by making it so much harder to mess with transactions via someone having the ability to double the hash between blocks, changing transactions, and getting the longest chain.  This could actually happen with a massively successful botnet that is kept idle except when needed, reducing the chance of people discovering the infection, increasing the spread of the bot and being able to control a ton of hash power for short periods of time.

And this is because only a very few of the world's computers are hashing, most people don't even know about crypto currencies, but they all have graphics cards that can be hijacked.

ASICs are usually not kept idle and thus, their high hash power would be very difficult, thousands of times harder, to double or triple. This makes the network more secure.

Anyway, Evan Duffield, our lead developer has said he and the team have come up with a potential solution that he will reveal soon.  Hopefully it'll pan out and we'll hear from him soon.  

One thing you can say about Dash, is that change is not something Dash fears.  Dash rolls with the changes (thanks RUSH)