I read it somewhere vividly drivechain require more than 51% consensus but forget where did i read that.
AFAIK the locked address is controlled by hashrate escrow provided by drivechain miners, so again drivechain miners could be rogue actor.
Anyway drivechain was proposed as a extra source of security budget, if cost of mining falls faster than hashrate can go up then onchain mining will still be competitively profitable. Second reason is no amount of dumbness & censorship can hold Bitcoin adoption forever, as the time goes on more & more people will abandon fiat & find ways to stack more sats therefore productivity will rise overall thus each sats will increase in value over time
"Everything divided by 21.000.000" but on my lifetime probably only 20 mils lol with quarter of em being lost
But if drivechain guys wanna do it that's their business