Get sued. You described a pure scam scheme. Of course there were underwrites and the usual dilution of responsibility, but even in this case "I wasn't able to predict that I can't handle it" will not work.
There is a need - Twitter is now an excellent platform for propaganda and manufacturing consent. If Twitter defaults on the loans, my assumption is the creditors take control, and Musk gets a ton of value from being in control of Twitter.
In developed countries it's not quite that straightforward, but "his" plane will be owned by Totally Not Musk LLC, not Musk himself, so any putative drugs on it are not his problem.
In developing countries, anything goes. I've paid $15 for "VIP" clearance in Indonesia, which means I sit in a lounge sipping tea and my passport comes back to me stamped without me ever seeing an immigration official.
Ketamine is diverted from official sources, usually where it is produced(India, Denmark are common). It's not worth it to make in a lab given how plentiful it is. Its everywhere, in every city. He probably has a guy that gets it online. You can easily buy ounces on darknet markets. I don't recommend you do this-- I just find it interesting how this stuff is all going on as a second blackmarket economy in absolutely huge quantities.
If he’s using it he probably just has a prescription or a doctor that provides it to him. Ketamine isn’t all that hard to get prescribed and it is, frankly, a pretty mellow drug.
Specifically ketamine is only a Schedule III controlled substance. Any physician can prescribe it to any patient and it's available through the normal pharmaceutical system. It's not one of those really dangerous, addictive Schedule I drugs like marijuana.
To not lose all of it. Musk is shareholders and while shareholders make the decisions(or at least decide who do) they are also last to get any value when things go to receivership.