People will see that corporations taking over masternodes would (or at least could) lead to privacy failure,
Your the one who doesn't "understand economic reasoning very well" with idle scaremongering remarks like that.
For that to happen, corporations would also have to overtake the coin supply which would simply be equivalent to comprehensive buying out of any cryptocurrency. From the perspective of 'security' a masternode isn't a PC, it's a portion of the coin supply.
Masternodes are profit-making businesses. There is no other reason to own one (other than idealism, which I discount in the long term).
Yes it requires a portion of the currency and if that's what it requires, that's what will happen. The argument about it being more profitable for them than to you still applies. If they can pay 1000 DRK and get a real return of say 1% while you only make a real return of 0% or -1% they will find it attractive to run a node while you will find it more attractive to cash out your DRK and go buy an island or something. So same effect.