For example, replication of effort for no reason other than to pump and dump. There are whole companies IPO'd for no reason other than to pump and dump. Or how about building garbage to produce future sales, like when Apple puts a garbage battery into a cellphone, or even cellphones without replaceable batteries? It's been years now that old phones were good enough to act as phones, if only they didn't fail prematurely. Cars are the same way; there are tons of parts which could be designed to last much longer, but they aren't because that would extend the sales cycle. Up to a third of a vehicle's lifetime energy consumption is in its production. It's not unrealistic to keep cars twice as long on average as we do now, if they're designed for easy maintenance and use durable parts like polyurethane bushings and heim joints. Dealerships don't want to lose thousands of dollars in revenue from refreshing tired suspension parts. But that's half bullshit work that doesn't even have to take place. Advertising firms producing advertising that nobody is even going to see. Consumer goods made in China, shipped to the USA, never sold because they are crap, shipped to the dollar store where most of them never sell, shipped to a landfill where they leach toxics into the ground. Nobody ever uses them, but we all pay for the energy cost of their production. Most buildings are built like total shit, and out of flammables. Big parts of cities catch on fire repeatedly throughout history, and then we build them all over again, out of more flammable materials. Even if they don't burn down, they'll fall down within a century because they're built out of thin sticks (remember when a 2x6 was a 2x6? Houses built that way which weren't washed away in a flood or burned down are still standing.) and Chinese sheet rock. We make coins whose monetary value is not only less than their actual cost of production, but less than their energy cost of production. We make thousands of tons of clothing no one will ever wear, which gets shipped to the first world, shipped to stores, put on racks, taken off racks, shipped to the third world, picked through to find the natural fabrics (rapidly vanishing due to climate change), and the remainder landfilled. The environmental cost of the textile industry is beyond ridiculous. We ask people to commute to jobs which could be done remotely, and how many of those jobs need to be done at all? Whole industries exist because of failings in our government, like health insurance. Cryptocurrency is a relatively minor line item, but it is literally burning up the biosphere to create tokens.
There are examples of waste literally everywhere you look, unless you're in a mud hut. Or maybe a shipping container home. Shipping containers are stacking up at ports because once they pass through certain ports and are fumigated with specific chemicals (usually horrendously toxic ones, as you might imagine) they are no longer permitted in certain other ports, because of the toxicity. Since we sell recycled steel to other nations for pennies on the ton, it's not actually worth it to recycle them, so in the main they are just sitting around rusting and losing intrinsic value when we could be using them to build fireproof, earthquake-proof buildings.
IANAE(conomist) and these are examples I could come up with just off the top of my head.