2a. Distributors that don't accept that go out of business, because none of the publishers from 1. want anything to do with them.
Supporting unethical practice can't be excused with fear of going out of business by the way. Also, publishers need distributors and users not any less than distributors and users need publishers, if not even more. Therefore voting with your wallet (on either distributor or user level) is not senseless. Except that distributors have more leverage on publishers, because of their scale, in comparison with an individual who buys only DRM-free products. Therefore distributors can be blamed more for DRM proliferation.
Publishers of new games (especially expensively developed new games) are more likely to fear a loss of revenue, especially in the crucial early period after release, without DRM.
I'm not really sure why bigger size of the budget should reduce the common sense of the publisher. Legacy publishers are obsessed with DRM, but DRM has nothing to do with revenue whatsoever. It doesn't reduce any piracy, and only cripples the experience for legitimate users. It's stupid from common sense business perspective, and there is an increasing amount of big budget games which come out DRM free. I view it as simply mentality issue. Legacy publishers can't understand that they should start being customer focused. New ones have no issues understanding it, therefore they don't use any DRM.