No such demo happened. They unveiled the 128K with that System 1.0 on stage at a special event. The Lisa has a different UI, but also can't do what's described.
There's no "computer icon". Dragging the System disk to trash ejects it on a classic Mac. If you burrow down into System, you can try deleting system files… which are locked and can't be deleted.
Is there other intelligent alien life in our Galaxy? Probably. Given how fast life formed on Earth, there must be millions of other life-bearing planets, and intelligence can't be that rare, but it might be short-lived.
Are there UFO sightings? Yes, people do see unidentified flying objects. Some of them can be explained, some cannot.
Are the UFOs aliens? I don't know, I'm a "curious agnostic" on the subject.
There's a LOT of UFO sightings, and evidence from good observers, including US Navy aviators. The US Air Force continues not to cooperate, and officially denies any sightings exist. The very enthusiastic refusal to look at evidence, aside from Project Blue Book, is suspicious.
It's technically plausible that someone within 50-ish light years of Earth could have heard our radio, sent a ship here, and use drones or manned ships to observe us without interacting. There could also be many other explanations.
We don't know, and until the last couple years there was no effort to investigate.
Bruce Bethke, the guy who actually invented cyberpunk and wrote the story Cyberpunk, wrote a book Head Crash. In which the VR hotsuit includes a "ProctoProd®" for bass. Bruce's predictions have turned out more accurate than anyone else's.
Some of Rudy's books are free, and they will blow your minds. Software, etc. and Postsingular as "what technology can do to us", and White Light as "how does infinity work in a story context"; he also has a couple non-fiction books on infinity.
Hard, computational SF aren't given nearly the respect they should, and these apply math, comp sci, and physics in a way nobody else does. If there's any civilization in the future, they'll be seen as visionary.
Runners-up are Robert L. Forward, Alastair Reynolds, but Forward has very little computation, and Reynolds doesn't show his math too often.
You can get the same basic CS education and write your own OS, it was in my 4th year CS classes, we mostly just implemented Minix 1.0 but you could get as weird as you want.
Then you have to make enough libraries to start porting things to it, or write everything from scratch.
One of my favorite hacks like this is SectorLisp, which fits a Lisp (sort of) in a boot sector.
There's other, more verbose, regular expression languages, for instance SRFI-115 for Scheme. But the hard part isn't the syntax, but actually thinking about patterns, so it won't help you any.
Just get the O'Reilly bat book and learn. So what if it overwrites 10% of your brain and you can't remember your mother's face, you'll have a useful skill.
I grew up during the Cold War, I had zero expectation that I'd live to adulthood, and I'm still unconvinced the world after 2000 exists. The way to cope is nihilism and/or activism.
Nuclear war, global warming makes the Earth uninhabitable, new plagues wipe out everyone, AI poisons us or creates nanotech grey goo, fascists take over and gas everyone who isn't them, a dinosaur-killer meteor hits the Earth again, eventually the Sun expands and fries the planet. You personally are going to die, probably long before any of those.
So you can either say "fuck it" and do your usual stuff anyway, or get involved in trying to stop or delay one of the disasters. Have fun with it.
Safari's fast, less crashy, highest privacy protections, and uses less memory per tab; I often have hundreds of tabs so that's important. It also has the best inspector, much better than Firebug. Add in StopTheMadness and an adblocker (currently using Ghostery), and it's pretty great.
Degoogled Chromium is useful for sites that don't work in Safari, or as a sandbox I don't mind crashing in development.
I've given up on Firefox, it's too fat and bloated.
I play a lot of MineTest, using the Asuna "game" (big modpack) and a huge custom set of mods, and have a game that's like MineCraft but utterly different. Others play the MineClone2 game, and it's fine, like MC 1.12 + some stuff. Repixture is an adorable mini-minecraft-like. There's a lot of people who use it more as creative, and many servers with various games.
It's definitely a little harder to set up the specific thing you want, but it's incredible how much variety there is.
I'm very interested in the "floating giant 4K screens" part, especially paired with a tiny MacBook Air, and some other uses seem fun. Real uses of AR passthru can be amazing, tagging everything around you with information. At $3500, it's half the price of a single XDR display.
But I'm waiting for gen 2 or later, there's no way the current weight & battery life are usable for my needs. It's a dev kit right now, and while I'm an iOS dev sometimes, it's too small a market to be profitable for me.
In addition to the things everyone else has brought up:
MacPorts gives you everything on any BSD or Linux machine, on your Mac.
iTerm2 is the best terminal on any platform, there's amazing capabilities in it. You didn't know your terminal was so inadequate!
AppleScript, Automator, and every programming language on Mac; Shortcuts, Pythonista, LispPad, & Hotpaw BASIC on iOS; make automation of the system and programming little tools incredibly easy. Everything is accessible to the power user, it's not like Linux where some GUI features are scriptable, and others you'll be writing a C++ program to reach some API because it's not exposed to anything.
As the old ad says (which got me to buy in): Sends other UNIX boxes to /dev/null
In the good old days, you had to learn assembly/machine language, C, and OS-level programming to get anything done. Even if you mostly worked on applications, you'd drop down and do something useful. At the time, this was writing machine language routines to call from BASIC. This is still a practical skill, for instance I mostly work in Scheme, but use C FFI to hook into native functionality, and debug in lldb.
Computer Science is supposed to be more math than practical, though when I took it we also did low-level graphics (BIOS calls & framebuffers), OS implementation, and other useful skills. These days almost all CS courses are job training, no theory and no implementation.
Younger programmers typically have no experience below the application language (Java, C#, Python, PHP) they work in, and only those with extensive CS degrees will ever see a C compiler. Even a shell, filesystems, and simple toolchains like Make are lost arts.
The MIT Missing Semester covers some of the mid-high levels of that, but there's no real training in the digital logic to OS levels.
Governmental research. There was Project Blue Book, as I mentioned, which was inconclusive and then ended.