If nvidia straight up just stopped selling any cards, declined all their client/customer base, and just put 100% of their global output to mining cryptocurrencies, I think it's a good chance nvidia can do a 50%+1 attack on both bitcoin and ethereum at the same time.
Once they successfully do the attack, they can take over the blockchains and allocate all cryptocurrencies to themselves, cash out, and it'd probably register as a good profit on their income statements.
Once they successfully do the attack, they can take over the blockchains and allocate all cryptocurrencies to themselves, cash out, and it'd probably register as a good profit on their income statements.