In
wikipedia it says that SegWit was activated on block 477120, but who begun that?
Segwit actually had a bunch of activation periods where miners are supposed to signal for the acceptance of Segwit and if the threshold of 95% is reached, then the rule would be activated 2 periods down. It was started after one of the difficulty periods and its support was implemented after 0.13.1.
The forum itself says on a quote that miners don't vote on changing consensus rules, only the order of the transactions. Seeing a change like that makes me wonder what else can the developers change. Should they have an impact on bitcoin? Whether if it's for good reason or not.
How did miners accept that change? They were not forced to update their bitcoin client.
See UASF and BIP91 with the reduced threshold. Bitcoin users are as important as miners; if you don't follow the users, then you're just mining on your own fork and the users are using another version which gives you zero economical benefits.
Even if the first one can be faced pretty easily by simply creating outputs on addresses that have never spent, the second one requires consensus change. I don't know what they can change in that case, probably use of stronger cryptography, but they will have to change something! Otherwise, bitcoin will be useless. Changing a consensus rule, that important, would sour lots of people. And that's because that moment, the developers would have to "touch" people's money. It'd be a consensus dead end.
Segwit was a controversial change from different camps. If it's something that puts the network (both users and miners alike) at risk, I can't see how they would oppose such a change.