Then they can all take to the streets and protest against the regime to make their PoV heard. Sure, the protesters will clash with the police/military who will use force against them, but if it's indeed the vast majority of people as you claim, against the regime, then the police/military cannot overwhelm over ~80 million people on the streets.

If the vast majority refuse to take to the streets in protest, then it means they silently or otherwise approve the government's actions. It's up to the Russian people to sort out their politics, by violent force if need be, if they're truly unhappy with the past 30 years of fake democracy and corruption among their leadership.

Same how in 1989 people and students in Romania took to the streets, en masse, to oust the dictator Nicolae Ceausescu, who refused to step down and had the military shoot the protestors. Spoiler alert: he still got ousted, so the excuse that "we can't protest in Russia against Putin" does not fly.