Things a coalition of evil miners can do on Bitcoin

If a miner coalition has 75% of hashrate for 6 months they can steal coins from a Drivechain without any risk, that's what the drivechain haters say.

What other evil things can a coalition of 75% hashrate do in 6 months?

• steal money from all open Lightning nodes on the network by opening channels to them, mining 3 blocks, spending the funds out on Lightning instantly, then rolling back the 3 blocks and canceling the channel.
• the above would eventually -- but not instantly and only after many steals have happened (even if they're not all perfectly coordinated and instant) -- cause Lightning to shrink in size a lot and become more of a closed friends network than truly open.
• only mine empty blocks and cause the mempool to be enormously clogged.
• refuse to use the mempool, force a proprietary API for transaction propagation with zero transparency and force other miners to use that same infrastructure too and extract a fee from them.
• censor anything and force other miners to censor too, at the threat of orphaning their blocks.
• easily cause so much confusion in the mining process that Bitcoin is deemed unusable and price falls drastically, miners can then buy at low price.