So Who'll keep the oil rigs running, who will resurface roads or fix plumbing in a world where people will still need to do the tough jobs. And why should they do those tough jobs when they can do what others are doing - nothing?
UBI isn't about doing nothing. It's about having enough to survive. If you can live in a tiny shoebox apartment and have enough for basic food and water and utilities, that's what UBI is about. With some roommates.
Now, you might find I didn't say anything about private bathrooms, or a kitchen, or more living space. Or luxuries like a TV, computer, etc. All that stuff is attached to a nice shared living quarter - so you and 3 other people who sleep in 2 bunk beds have a room, and everything else is shared. That's UBI. You'll survive, you'll live. You're not on the street in a tent.
But I'm sure you probably want more. UBI allows for that - that's why you go to work. You earn money, so you can spend it on better things - perhaps a private apartment so you can have your own bedroom, bathroom, kitchen and living space. Your own TV, your own computer. Gaming consoles.
Perhaps you want a car. UBI gives you bus passes. Perhaps you want a NICE car, or SUV, or truck.
So your oil rig worker could do nothing - but then he'd lose all the lifestyle he has - sure he's used to living in a dorm and such, but he's also used to going to a private house and driving a car and other things.
UBI won't affect that end of the economy at all. What it would do is disrupt the lower end - where your waiters and waitresses who ear $3.25 an hour (plus tips) who already live in a shoebox with 3 other roommates already live.
AI is coming after the low end - the entry level stuff. The stuff that pays for the low end of living, so either everyone graduating today can't get a job and we end up with fields of tents of homeless people who can't get a job because there are no jobs, or you provide those people with basic shelter and survival. And maybe the opportunity to work on something because they want to own a house someday as well.
If I took you from your comfortable house into a single room with nothing in it but a bed with the expectation you can be a slob and live like that, would you take it? Or would you want to be able to live in a nice private accommodations and such?
UBI doesn't means living in luxury, it just means having the basics. And last I checked, most people would prefer having more than the basics - whatever those may be.
Your high paying jobs of trades and such? People still want those - you aren't going to convince me that a CEO making half a billion a year would rather give up all that just to do nothing.