I think your idea on what "technology" consists of, is stuck in the 90s.
Todays advances in AI and Robotics - and especially the combination of both - is opening a big can of worms.
Let's take a realistic trip to a near future of an all-connected world (the internet of things)... I'm not saying that this is how it will be. I'm saying that this scenario is perfectly feasable with today's technological trend and it would only take 2 decades at most to acquire all necessary technology.
It's a typical saturday. You need to do your grosseries.
Currently, you would get in your car, drive to the supermarket, fill your chart, wait in line, have everything scanned by the cashier, you pay, load your car, drive home and unload everything.
Step 1: how this will change: you wouldn't drive your car. Instead, you tell your car to drive you.
Step 2: you no longer fill your own shopping chart or wait in line. Or as a cashier, you no longer have that job. Because now, the supermarket is like a giant gumball machine. You send your list, through some app prob, your car drives you to the supermarket machine, you identify yourself and out comes a shopping chart with everything you ordered.
Step 3: your car no longer drives you. You stay at home and you just tell your car to go pick up your grosseries. The supermarket machine now is able to load grosseries into/unto a car through a universal mechanism.
Step 4: you no longer tell you car to pick it up. your "smart home" knows that you need grosseries. It's an AI engine that powers it, so it also knows, perhaps even better then you yourself, what you want and need. It sends the shopping list automatically. At some point, your car simply asks you "is it okay for me to go pick your grosseries now?", to make sure that you don't need the car. Or, off course, a supermarket drone just delivers it to your house.
That supermarket used to employ some 30 people. Now it only requires a maintenance crew of perhaps 3. And if they need to work, it means the machine isn't working.
Now, consider this level of technology in all the industries that need to exist in order for that supermarket machine to be there... It needs products. So you require factories and distribution.
Again, considering the rapid advances in robotics, I'm having trouble finding examples of things that are currently done by humans in the "production" process, that couldn't be done by robots. And likely done better as well.
The technology that makes your car drive on auto-pilot, will also make just about every driver job in distribution obsolete. That goes for all transportation. Boats, cars, trucks, airplanes, trains,...
And you can think about this in the exact same way for just about all industries.
Like a simple bar for instance....
What can a waitress do, that a drone can't do - except perhaps dropping a tray of full glasses?
All in all, I think the estimate of 40% job loss due to this trend, is actually rather optimistic. I think it will be a lot more.
Plumbers and handymen - okay. But please note that those are already existing jobs. In and in the future I painted above, we won't be requiring more of them...
As for security guards... they will become obsolete as well. Or at the VERY least, we will require FAR less of them. Smart security systems are well on their way. In fact, I just watched an incredible demo of such a system in context of "safety at the workplace".
Smart camera's easily detected safety violations and notified those responsible to take action. Through facial recognition, it was also easily able to notify managers if certain workers were using tools that they weren't authorized to use.
In case of actual accidents (fires, explosions, wounded humans, etc), it also automatically notified emergency services.
This system does a FAR better job then an entire team of professional safety guards. Similar systems could easily be deployed for overall security. No more need for plenty of patrolling officers. Or at least: a lot less need for such.
I beg the differ. Already today, it is problematic to feed all humans. Human population is still quickly rising. Global warming won't make it easier to grow even more food. And that's not even counting drinkable water, which will be even more of a problem.
If anything, I predict the price of food and water to rise.
I don't see why.
Currently, the largest cost for businesses, big or small, are the employees.
There's a reason why big factories make use of robots already today. Do you really think they would deploy automated assembly lines today, if it were actually cheaper (ie: more profit) to have humans do those jobs?