Scientists have been recording from monkey’s brains for decades. There are labs around the world (although thankfully fewer than 10 years ago) that implant brain electrodes and could train a monkey to play pong without a controller if that was the goal. The monkeys in other labs aren’t dropping dead.
For instance, a monkey that was in the lab next to me for over a decade recently moved to the Retirement Sanctuary for Laboratory Animals to finally live outside (near Gonzalez, TX). Lab animals have pretty lousy lives, but it is healthy and cared for by people who wanted to minimize the shittiness.
Neuralink differs in 2 main ways; they have an untested power supply that they seal inside the skull and they don’t give a shit about the monkeys. Musk imagines an implant in humans that stimulates your brain like in scifi movies, and doesn’t care about having monkeys die to troubleshoot problems with the stimulator.
Also, clinical trials of chronic stimulation of visual cortex for humans with retinal blindness is progressing well. The (obviously non-neuralink) implants don’t cause infections and patients gain crude image formation. If we just remove Musk from the equation the future won’t be so dystopian that we have to flee to Mars