I don’t know about how the witnesses did earn their stake.
Most of the current consensus witnesses didn't mine their stake by the looks of the list. There really weren't so many miners and as said, the mining wasn't the problem, the way Steemit Inc mined theirs is.
If Justin sees it as an act of war, it would be good evidence as to why it was done. With that much free stake, it takes some level of maturity to use it wisely.
I was one of the early miners and I have a pretty good idea who the others are. I believe about 5 of the current top 20 witnesses were early miners. The rest were not. Some don't even have all that much Steem, but they are trusted and respected by the community so they are voted in.
Yes, I have dug around enough over the years to be able to pick most from a lineup :) At the moment, it isn't a bad mix of old and new, developer and community orientated.
Why is your mining considered fair and non-ninja, while Steem Inc's mining is ninja and unfair?
I had no privileged information of being a VC-backed company with significant funding to carry forward the effort and make it worth something, which removed much or all of the the risk of spending money on mining, from their perspective alone. I also didn't deliberately withhold that information from everyone else, or order to deliberately rig the outcome the way they wanted.
From my perspective as a miner (as well as that of other non-Steemit miners), it had a high risk of never getting further development, never getting listed on an exchange and never having any real value, like many other coins at that time which showed up as only an announcement post. But they knew quite well that wasn't true.
Moving on, I didn't have the correct mining instructions while I gave everyone else broken ones. I hadn't spent months working with the code while everyone else only had a day or two to try to get an incomplete idea of what was in it and how to mine efficiently with limited or no correct documentation. I didn't reset the chain when things didn't go my way (in fact I was hurt by that, as I spent money to mine on the first chain), and finally I didn't make any promises or statements about dedicating my stake to developing the ecosystem or not voting.
Finally, I wouldn't say that Steemit's ninja-mining wasn't 'legitimate', but when they went and sold others on why we should invest our own money and effort into something with a very unbalanced and centralized stake ownership, they made promises and statements about how the stake would be used to get that support. I consider likewise consider it legitimate to hold them and the ninja-mined stake to that model and usage.
So, in summary, I'm perfectly accepting of their stake, as long as it is used as promised, which is that it be non-voting and used to develop the ecosystem.