53 billion dollars in December 2017 for discarded phones/laptops/electronic devices only.
But what about EVERYTHING ELSE that's thrown away or burned?
Tires, cars, paper, furniture...
How much do you think that amounts to?
If there is as estimate somewhere about $53B per month of e-waste. That sounds a lot like they're basing that on the purchase price, not the value when it's discarded. And that's a pretty useless valuation, as it simplifies to how much money is spent per month, since everything will eventually become waste.
Taking the entire food industry as an example, if you consider only the purchase price, then the entire industry is 100% waste over a very short period of time. In fact, you could argue that it's even more than 100% waste, since people will actually pay to have the waste removed.
Before you call something "waste", to have any practical meaning at all, you need to subtract off the value it provided to the consumer. Since that's really hard to do, I can see a journalist just using the purchase price to make a dramatic headline, rather than producing any useful information.
Pick a country with reasonably accurate data. Start with statistics on a country's GDP. Break down the GDP into categories of services, durable goods, non-durable goods, the finer-grain the better.  Decide which categories you regard as in-scope (e.g. services consumed? probably out of scope. durable goods like cars, furnishings, houses? electronic stuff? industrial machinery? probably in scope). Do you want to include stuff like food? Oil? Then, for each category in scope, estimate (1) the expected lifespan of the good before it is disposed of, and (2) the residual fraction of the good's original value that remains at disposal time that is lost but could be captured by better recycling/reuse/scrap recovery, etc.
E.g. in 2019 the US spent 530 billion dollars on motor vehicles and parts. The average lifespan of a motor vehicle is about 12 years. So we could estimate that every year, about (1/12)th of motor values and parts reach end of life. So we could say that (1/12)th of the original value reaches end of life -- so about 44 billion dollars per year. Now, what fraction of the original value is still recoverable at end-of-life? Probably something in the range of 10% -- 1% . So maybe there's residual value of 4.4 - 0.4 billion dollars of motor vehicles and parts that reach end of life every year in the US. Arguably this figure should be net of recovery costs (e.g. labour, energy, capital machinery to recover working parts or shred broken stuff). Some fraction of this will currently be recovered and reused/recycled. The remainder will be lost.
To crudely translate from US GDP to the world GDP, multiply by 4.
So we might estimate that globally there's about 17 -- 2 billion dollars of residual value in motor vehicles and parts reach end of life, some of which is recovered, some of which isn't.
 data source for the US: https://www.bea.gov/data/gdp/gross-domestic-product See https://www.bea.gov/system/files/2020-01/gdp4q19_adv.xlsx ; table 3 "gross domestic product: level and change from preceeding period"
e.g. some physical products will be disposed of when they have degraded to the extent that it does not make economic sense to repair them, or for someone else buy and reuse/repair them, given the costs of doing so compared to e.g. just buying a comparable new item or a comparable used item in better condition. so they cost a lot to buy in the first place, but now they roughly zero value, or perhaps a very low value as scrap.
That said, some other perfectly good stuff (with relatively high re-use value or scrap value) will be thrown away.
Why do you want to estimate this number? If you have a particular use in mind, it might be possible to come up with a more relevant and useful statistic.